Class 7 : Maths โ Lesson 3. A Peek Beyond the Point
EXPLANATION AND ANALYSIS
๐ต Introduction: Moving Beyond Whole Numbers
๐ง In earlier classes, we mostly worked with whole numbers and integers. However, many situations in daily life involve numbers that are not whole. For example, the length of a ribbon may be 2.5 metres, the weight of a packet may be 1.75 kilograms, or the time taken to complete a race may be 3.2 seconds.
๐ฟ Such numbers help us measure quantities more accurately. These numbers are called decimal numbers. This chapter introduces us to the idea of numbers that go beyond the point, that is, numbers written using a decimal point.
๐ข Meaning of Decimal Numbers
๐ง A decimal number is a number that has a decimal point and digits after it.
๐น The part before the decimal point shows whole units
๐น The part after the decimal point shows parts of a whole
๐ Example
In the number 4.7
๐น 4 represents whole units
๐น 7 represents parts of a unit
๐ก Concept:
Decimals help us represent quantities that lie between two whole numbers.
๐ต Place Value in Decimal Numbers
๐ง Just like whole numbers, digits in decimal numbers also have place values.
๐น Ones
๐น Tenths
๐น Hundredths
๐น Thousandths
๐ Example
In the number 3.456
๐น 4 is in the tenths place
๐น 5 is in the hundredths place
๐น 6 is in the thousandths place
๐ก Concept:
Each place to the right of the decimal point is one-tenth of the previous place.
๐ข Reading and Writing Decimal Numbers
๐ง Decimal numbers are read by reading the whole number part first, then saying โpointโ, followed by each digit after the point.
๐ Example
2.35 is read as
Two point three five
โ๏ธ Note:
Digits after the decimal point are read individually, not as a whole number.
๐ต Writing Decimals from Words
๐ง To write decimal numbers given in words, identify the place value of each part.
๐ Example
Three and five tenths
๐น Three = 3
๐น Five tenths = 0.5
๐น Decimal number = 3.5
๐ก Concept:
The word โtenthsโ shows one digit after the decimal point, while โhundredthsโ shows two digits.
๐ก Comparing Decimal Numbers
๐ง Decimal numbers can be compared just like whole numbers, but with special care.
๐น First compare the whole number part
๐น If equal, compare digits after the decimal point
๐ Example
Compare 4.25 and 4.3
๐น Whole number part is same
๐น Compare tenths: 2 < 3
๐น So 4.3 is greater
โ๏ธ Note:
Write the decimals with the same number of decimal places to compare easily.
๐ข Ordering Decimal Numbers
๐ง Ordering means arranging numbers from smallest to greatest or vice versa.
๐น Ascending order: smallest to greatest
๐น Descending order: greatest to smallest
๐ Example
Arrange 2.5, 2.35, 2.8
Ascending order
2.35 < 2.5 < 2.8
๐ต Using Zeros in Decimal Numbers
๐ง Adding zeros after the decimal point does not change the value of a decimal number.
๐ Example
2.5 = 2.50 = 2.500
๐ก Concept:
Zeros are often added to make decimals easier to compare or calculate.
๐ก Decimal Numbers on the Number Line
๐ง Decimal numbers can be shown clearly on a number line.
๐น Divide the space between two whole numbers into equal parts
๐น Each part represents tenths or hundredths
๐ Example
The number 3.4 lies between 3 and 4, closer to 3 than to 4.
โ๏ธ Note:
The number line helps us visualise the position of decimal numbers.
๐ข Decimals in Daily Life
๐ง Decimal numbers are used widely in everyday life.
๐น Money such as 12.50 rupees
๐น Length like 1.75 metres
๐น Weight like 2.3 kilograms
๐น Time like 4.5 seconds
๐ก Concept:
Decimals make measurements more precise and meaningful.
๐ด Common Mistakes to Avoid
๐ด Ignoring place value after the decimal point
๐ด Comparing decimals without aligning decimal points
๐ด Thinking that 2.5 is smaller than 2.35
๐ด Misreading decimal numbers
โ๏ธ Note:
Always compare decimals by looking at place values step by step.
๐ข Importance of Learning Decimals
๐ง Learning decimal numbers helps us:
๐น Measure quantities accurately
๐น Understand money calculations
๐น Read scientific data
๐น Prepare for higher mathematics
This chapter builds a strong foundation for fractions, percentages, and algebra.
๐ Summary
๐ต Decimal numbers represent parts of a whole
๐ข They contain a decimal point
๐ก Place value extends beyond the decimal point
๐ด Tenths, hundredths, and thousandths show precision
๐ต Decimals can be compared and ordered
๐ข Zeros after the decimal do not change value
๐ก Decimals are widely used in daily life
๐ Quick Recap
๐ Quick Recap
๐ต Decimal numbers go beyond whole numbers
๐ข Decimal point separates whole and fractional parts
๐ก Place value continues after the point
๐ด Decimals help in accurate measurement
๐ต Decimals are essential in daily life
——————————————————————————————————————————————————————————————————————————–
TEXTBOOK QUESTIONS
๐ต A TENTH PART
๐ โ Arrange these lengths in increasing order:
(a) 9/10
(b) 1 7/10
(c) 130/10
(d) 13 1/10
(e) 10 5/10
(f) 7 6/10
(g) 6 7/10
(h) 4/10
๐ โ Answer:
๐น Convert all to tenths for easy comparison.
๐ธ 9/10 = 9/10
๐ธ 1 7/10 = 17/10
๐ธ 130/10 = 130/10
๐ธ 13 1/10 = 131/10
๐ธ 10 5/10 = 105/10
๐ธ 7 6/10 = 76/10
๐ธ 6 7/10 = 67/10
๐ธ 4/10 = 4/10
๐น Arrange from smallest to largest (by numerators).
โ๏ธ Final:
4/10, 9/10, 1 7/10, 6 7/10, 7 6/10, 10 5/10, 130/10, 13 1/10
๐ โ Arrange the following lengths in increasing order:
4 1/10, 4/10, 41/10, 1/10.
๐ โ Answer:
๐น Write all lengths in tenths.
๐ธ 4 1/10 = 41/10
๐ธ 4/10 = 4/10
๐ธ 41/10 = 41/10
๐ธ 1/10 = 1/10
๐น Compare numerators.
โ๏ธ Final:
1/10, 4/10, 4 1/10, 41/10
๐ โ Sonu is measuring some of his body parts. The length of Sonuโs lower arm is 2 7/10 units, and that of his upper arm is 3 6/10 units. What is the total length of his arm?
๐ โ Answer:
๐น Add whole-number parts.
๐ธ 2 + 3 = 5
๐น Add fractional parts.
๐ธ 7/10 + 6/10 = 13/10
๐น Combine whole and fractional parts.
๐ธ 5 + 13/10
๐น Convert improper fraction.
๐ธ 13/10 = 1 + 3/10
๐น Add again.
๐ธ 5 + 1 + 3/10 = 6 3/10
โ๏ธ Final:
The total length of Sonuโs arm is 6 3/10 units.
๐ โ The lengths of the body parts of a honeybee are given. Find its total length.
Head: 2 3/10 units
Thorax: 5 4/10 units
Abdomen: 7 5/10 units
๐ โ Answer (Teacher-like explanation):
๐น We are given three lengths written as mixed numbers.
๐น To add them easily, we first add whole parts and tenths parts separately.
๐น Step 1: Add the whole-number parts
๐ธ Head = 2 units
๐ธ Thorax = 5 units
๐ธ Abdomen = 7 units
๐ธ Total whole units = 2 + 5 + 7 = 14
๐น Step 2: Add the tenths
๐ธ 3/10 + 4/10 + 5/10
๐ธ = 12/10
๐น Step 3: Convert extra tenths into units
๐ธ 12/10 means 1 whole unit and 2/10
๐ธ So, 12/10 = 1 + 2/10
๐น Step 4: Add everything together
๐ธ 14 + 1 + 2/10 = 15 2/10
โ๏ธ Final:
The total length of the honeybee is 15 2/10 units.
๐ โ The length of Shylajaโs hand is 12 4/10 units, and her palm is 6 7/10 units, as shown in the picture. What is the length of the longest (middle) finger?
๐ โ Answer (Teacher-like explanation):
๐น The hand length includes the palm and the finger.
๐น To find only the finger length, we subtract the palm length from the total hand length.
๐น Step 1: Write the subtraction clearly
๐ธ (12 4/10) โ (6 7/10)
๐น Step 2: Separate whole numbers and tenths
๐ธ (12 โ 6) + (4/10 โ 7/10)
๐น Step 3: Subtract the whole numbers
๐ธ 12 โ 6 = 6
๐น Step 4: Observe the tenths carefully
๐ธ We cannot subtract 7/10 from 4/10
๐ธ So, we regroup 1 unit from 6
๐น Step 5: Regroup 1 unit as tenths
๐ธ 1 unit = 10/10
๐ธ 6 becomes 5 + 10/10
๐น Step 6: Subtract the tenths
๐ธ 10/10 โ 3/10 = 7/10
๐น Step 7: Combine the result
๐ธ 5 + 7/10 = 5 7/10
๐ก Concept:
Regrouping helps when the fractional part of the minuend is smaller than the fractional part of the subtrahend.
โ๏ธ Final:
The length of the longest (middle) finger is 5 7/10 units.
๐ โ Try computing the difference by converting both lengths to tenths.
A Celestial Pearl Danioโs length is 2 4/10 cm, and the length of a Philippine Goby is 9/10 cm. What is the difference in their lengths?
๐ โ Answer (Teacher-like explanation):
๐น To find the difference, both lengths should be written in the same form.
๐น We convert both lengths into tenths.
๐น Step 1: Convert mixed number to tenths
๐ธ 2 4/10 = 24/10
๐น Step 2: Write the second length in tenths
๐ธ 9/10 = 9/10
๐น Step 3: Subtract the lengths
๐ธ 24/10 โ 9/10 = 15/10
๐น Step 4: Convert back to mixed number
๐ธ 15/10 = 1 5/10
โ๏ธ Final:
The difference in their lengths is 1 5/10 cm.
๐ โ How big are these fish compared to your finger?
๐ โ Answer (Teacher-like explanation):
๐น The lengths of both fish are less than 3 cm.
๐น A finger of a student is usually longer than 5 cm.
๐น Therefore, both fish are shorter than a finger.
โ๏ธ Final:
Both fish are shorter than a finger.
๐ โ Observe the given sequences of numbers. Identify the change after each term and extend the pattern:
๐ โ (a) 4, 4 3/10, 4 6/10, ___, ___, ___
๐ โ Answer (Teacher-like explanation):
๐น Write the numbers in tenths.
๐ธ 4 = 4 0/10
๐น Find the change between terms.
๐ธ 4 0/10 โ 4 3/10 = +3/10
๐ธ 4 3/10 โ 4 6/10 = +3/10
๐น The pattern increases by 3/10 each time.
โ๏ธ Final:
4 9/10, 5 2/10, 5 5/10
๐ โ (b) 8 2/10, 8 7/10, 9 2/10, ___, ___, ___
๐ โ Answer (Teacher-like explanation):
๐น Find the difference between terms.
๐ธ 8 2/10 โ 8 7/10 = +5/10
๐ธ 8 7/10 โ 9 2/10 = +5/10
๐น The pattern increases by 5/10.
โ๏ธ Final:
9 7/10, 10 2/10, 10 7/10
๐ โ (c) 7 6/10, 8 7/10, ___, ___, ___
๐ โ Answer (Teacher-like explanation):
๐น Convert to tenths.
๐ธ 7 6/10 = 76/10
๐ธ 8 7/10 = 87/10
๐น Find the change.
๐ธ 87/10 โ 76/10 = 11/10 = 1 1/10
๐น The pattern increases by 1 1/10.
โ๏ธ Final:
9 8/10, 10 9/10, 12 0/10
๐ โ (d) 5 7/10, 5 3/10, ___, ___, ___
๐ โ Answer (Teacher-like explanation):
๐น Observe the change.
๐ธ 5 7/10 โ 5 3/10 = โ4/10
๐น The pattern decreases by 4/10.
โ๏ธ Final:
4 9/10, 4 5/10, 4 1/10
๐ โ (e) 13 5/10, 13, 12 5/10, ___, ___, ___
๐ โ Answer (Teacher-like explanation):
๐น Write all terms in tenths.
๐ธ 13 5/10 โ 13 0/10 โ 12 5/10
๐น Each step decreases by 5/10.
โ๏ธ Final:
12 0/10, 11 5/10, 11 0/10
๐ โ (f) 11 5/10, 10 4/10, 9 3/10, ___, ___, ___
๐ โ Answer (Teacher-like explanation):
๐น Find the difference.
๐ธ 11 5/10 โ 10 4/10 = โ1 1/10
๐ธ 10 4/10 โ 9 3/10 = โ1 1/10
๐น The pattern decreases by 1 1/10 each time.
โ๏ธ Final:
8 2/10, 7 1/10, 6 0/10
๐ต A HUNDREDTH PART
๐ โ Figure it Out โ Find the sums and differences
๐ โ (a) 3/10 + 3 4/100
๐ โ Answer (Teacher-like explanation):
๐น First, both numbers should be written with the same denominator.
๐น 3/10 can be written in hundredths.
๐น Step 1: Convert 3/10 into hundredths
๐ธ 3/10 = 30/100
๐น Step 2: Write both numbers clearly
๐ธ 30/100 + 3 4/100
๐น Step 3: Add fractional parts
๐ธ 30/100 + 4/100 = 34/100
๐น Step 4: Add the whole number
๐ธ 3 + 34/100
โ๏ธ Final:
3 34/100
๐ โ (b) 9 5/10 7/100 + 2 1/10 3/100
๐ โ Answer (Teacher-like explanation):
๐น Add whole parts, tenths, and hundredths separately.
๐น Step 1: Add whole numbers
๐ธ 9 + 2 = 11
๐น Step 2: Add tenths
๐ธ 5/10 + 1/10 = 6/10
๐น Step 3: Add hundredths
๐ธ 7/100 + 3/100 = 10/100
๐น Step 4: Convert 10/100 into tenths
๐ธ 10/100 = 1/10
๐น Step 5: Add tenths again
๐ธ 6/10 + 1/10 = 7/10
๐น Step 6: Combine all parts
๐ธ 11 7/10
โ๏ธ Final:
11 7/10
๐ โ (c) 15 6/10 4/100 + 14 3/10 6/100
๐ โ Answer (Teacher-like explanation):
๐น Add each part carefully.
๐น Step 1: Add whole numbers
๐ธ 15 + 14 = 29
๐น Step 2: Add tenths
๐ธ 6/10 + 3/10 = 9/10
๐น Step 3: Add hundredths
๐ธ 4/100 + 6/100 = 10/100
๐น Step 4: Convert 10/100
๐ธ 10/100 = 1/10
๐น Step 5: Add tenths again
๐ธ 9/10 + 1/10 = 10/10 = 1
๐น Step 6: Add to whole number
๐ธ 29 + 1 = 30
โ๏ธ Final:
30
๐ โ (d) 7 7/100 โ 4 4/100
๐ โ Answer (Teacher-like explanation):
๐น Subtract whole numbers and hundredths separately.
๐น Step 1: Subtract whole numbers
๐ธ 7 โ 4 = 3
๐น Step 2: Subtract hundredths
๐ธ 7/100 โ 4/100 = 3/100
๐น Step 3: Combine
๐ธ 3 3/100
โ๏ธ Final:
3 3/100
๐ โ (e) 8 6/100 โ 5 3/100
๐ โ Answer (Teacher-like explanation):
๐น Step 1: Subtract whole numbers
๐ธ 8 โ 5 = 3
๐น Step 2: Subtract hundredths
๐ธ 6/100 โ 3/100 = 3/100
๐น Step 3: Combine
๐ธ 3 3/100
โ๏ธ Final:
3 3/100
๐ โ (f) 12 6/100 2/100 โ 9/10 9/100
๐ โ Answer (Teacher-like explanation):
๐น Convert everything into hundredths to avoid confusion.
๐น Step 1: Convert tenths to hundredths
๐ธ 9/10 = 90/100
๐น Step 2: Write numbers clearly
๐ธ 12 8/100 โ 9 90/100
๐น Step 3: Regroup 1 whole unit
๐ธ 12 = 11 + 100/100
๐น Step 4: Subtract hundredths
๐ธ 108/100 โ 90/100 = 18/100
๐น Step 5: Subtract whole numbers
๐ธ 11 โ 9 = 2
๐น Step 6: Combine
๐ธ 2 18/100
โ๏ธ Final:
2 18/100
๐ต ADDITION AND SUBTRACTION OF DECIMALS
๐ โ 1. Find the sums
๐ โ (a) 5.3 + 2.6
๐ โ Answer (Teacher-like explanation):
๐น Write decimals one below the other, aligning the decimal points.
๐ธ 5.3
๐ธ 2.6
๐น Add tenths first.
๐ธ 3 + 6 = 9
๐น Add whole numbers.
๐ธ 5 + 2 = 7
โ๏ธ Final:
7.9
๐ โ (b) 18 + 8.8
๐ โ Answer:
๐น Write 18 as 18.0 to match decimal places.
๐ธ 18.0
๐ธ 8.8
๐น Add tenths and whole numbers.
โ๏ธ Final:
26.8
๐ โ (c) 2.15 + 5.26
๐ โ Answer:
๐น Align decimal points carefully.
๐น Add hundredths, then tenths, then whole numbers.
๐ธ 0.15 + 0.26 = 0.41
๐ธ 2 + 5 = 7
โ๏ธ Final:
7.41
๐ โ (d) 9.01 + 9.10
๐ โ Answer:
๐น Align decimals.
๐น Add hundredths and tenths first.
๐ธ 0.01 + 0.10 = 0.11
๐ธ 9 + 9 = 18
โ๏ธ Final:
18.11
๐ โ (e) 29.19 + 9.91
๐ โ Answer:
๐น Add hundredths.
๐ธ 0.19 + 0.91 = 1.10
๐น Regroup 1 whole.
๐ธ 29 + 9 + 1 = 39
โ๏ธ Final:
39.10
๐ โ (f) 0.934 + 0.6
๐ โ Answer:
๐น Write 0.6 as 0.600.
๐น Add thousandths, hundredths, tenths.
โ๏ธ Final:
1.534
๐ โ (g) 0.75 + 0.03
๐ โ Answer:
๐น Add hundredths.
โ๏ธ Final:
0.78
๐ โ (h) 6.236 + 0.487
๐ โ Answer:
๐น Add thousandths carefully.
๐น Regroup where needed.
โ๏ธ Final:
6.723
๐ โ 2. Find the differences
๐ โ (a) 5.6 โ 2.3
๐ โ Answer:
๐น Subtract tenths, then whole numbers.
โ๏ธ Final:
3.3
๐ โ (b) 18 โ 8.8
๐ โ Answer:
๐น Write 18 as 18.0.
๐น Subtract tenths carefully.
โ๏ธ Final:
9.2
๐ โ (c) 10.4 โ 4.5
๐ โ Answer:
๐น Regroup 1 unit if needed.
โ๏ธ Final:
5.9
๐ โ (d) 17 โ 16.198
๐ โ Answer:
๐น Write 17 as 17.000.
๐น Regroup across decimal places.
โ๏ธ Final:
0.802
๐ โ (e) 17 โ 0.05
๐ โ Answer:
๐น Write 17 as 17.00.
โ๏ธ Final:
16.95
๐ โ (f) 34.505 โ 18.1
๐ โ Answer:
๐น Write 18.1 as 18.100.
๐น Subtract step-by-step.
โ๏ธ Final:
16.405
๐ โ (g) 9.9 โ 9.09
๐ โ Answer:
๐น Write 9.9 as 9.90.
๐น Subtract hundredths.
โ๏ธ Final:
0.81
๐ โ (h) 6.236 โ 0.487
๐ โ Answer:
๐น Subtract thousandths with regrouping.
โ๏ธ Final:
5.749
๐ต FIGURE IT OUT ?
๐ โ 1. Convert the following fractions into decimals:
๐ โ (a) 5/100
๐ โ Answer (Teacher-like explanation):
๐น The denominator is 100, so the fraction represents hundredths.
๐น Move the decimal point two places to the left.
๐ธ 5/100 = 0.05
โ๏ธ Final:
0.05
๐ โ (b) 16/1000
๐ โ Answer:
๐น The denominator is 1000, so the fraction represents thousandths.
๐น Move the decimal point three places to the left.
๐ธ 16/1000 = 0.016
โ๏ธ Final:
0.016
๐ โ (c) 12/10
๐ โ Answer:
๐น The denominator is 10, so the fraction represents tenths.
๐น Move the decimal point one place to the left.
๐ธ 12/10 = 1.2
โ๏ธ Final:
1.2
๐ โ (d) 254/1000
๐ โ Answer:
๐น Denominator 1000 means thousandths.
๐น Move the decimal point three places to the left.
๐ธ 254/1000 = 0.254
โ๏ธ Final:
0.254
๐ โ 2. Convert the following decimals into a sum of tenths, hundredths and thousandths:
๐ โ (a) 0.34
๐ โ Answer:
๐น The digit 3 is in the tenths place.
๐น The digit 4 is in the hundredths place.
๐ธ 0.34 = 3/10 + 4/100
โ๏ธ Final:
3/10 + 4/100
๐ โ (b) 1.02
๐ โ Answer:
๐น 1 is the whole number.
๐น 0 tenths and 2 hundredths.
๐ธ 1.02 = 1 + 2/100
โ๏ธ Final:
1 + 2/100
๐ โ (c) 0.8
๐ โ Answer:
๐น 8 is in the tenths place.
๐ธ 0.8 = 8/10
โ๏ธ Final:
8/10
๐ โ (d) 0.362
๐ โ Answer:
๐น 3 tenths, 6 hundredths, 2 thousandths.
๐ธ 0.362 = 3/10 + 6/100 + 2/1000
โ๏ธ Final:
3/10 + 6/100 + 2/1000
๐ โ 3. What decimal number does each letter represent in the number line below?
๐ โ
Answer (Teacher-like explanation):
๐น The arrow a is on the tick just after 6.44, so
๐ธ a = 6.46
๐น The arrows c and b are the first two ticks to the right of 6.5, so
๐ธ c = 6.52
๐ธ b = 6.54
โ๏ธ Final (Correct):
๐ โ
a = 6.46, c = 6.52, b = 6.54
๐ โ 4. Arrange the following quantities in descending order:
๐ โ (a) 11.01, 1.011, 1.101, 11.10, 1.01
๐ โ Answer:
๐น Compare whole numbers first.
โ๏ธ Final:
11.10, 11.01, 1.101, 1.011, 1.01
๐ โ (b) 2.567, 2.675, 2.768, 2.499, 2.698
๐ โ Answer:
โ๏ธ Final:
2.768, 2.698, 2.675, 2.567, 2.499
๐ โ (c) 4.678 g, 4.595 g, 4.600 g, 4.656 g, 4.666 g
๐ โ Answer:
โ๏ธ Final:
4.678 g, 4.666 g, 4.656 g, 4.600 g, 4.595 g
๐ โ (d) 33.13 m, 33.31 m, 33.133 m, 33.331 m, 33.313 m
๐ โ Answer:
โ๏ธ Final:
33.331 m, 33.313 m, 33.31 m, 33.133 m, 33.13 m
๐ โ 5. Using the digits 1, 4, 0, 8, and 6 make:
๐ โ (a) the decimal number closest to 30
๐ โ Answer:
๐น We must use only digits 1,4,0,8,6 exactly once.
๐น To be closest to 30, the nearest possible whole-part using these digits is 40 (because we cannot form 29 or 30 without digit 2 or 3).
๐น To make it closest, keep the decimal part as small as possible while using remaining digits.
โ๏ธ Final (Correct):
๐ โ
40.168
๐ โ (b) the smallest possible decimal number between 100 and 1000
๐ โ Answer:
๐น The smallest number is formed by keeping the hundreds digit as small as possible.
โ๏ธ Final:
104.68
๐ โ 6. Will a decimal number with more digits be greater than a decimal number with fewer digits?
๐ โ Answer:
๐น No.
๐น The value of a decimal depends on its place value, not the number of digits.
โ๏ธ Final:
A decimal with more digits is not always greater.
๐ โ 7. Mahi purchases 0.25 kg of beans, 0.3 kg of carrots, 0.5 kg of potatoes, 0.2 kg of capsicums, and 0.05 kg of ginger. Calculate the total weight.
๐ โ Answer:
๐น Add all weights.
๐ธ 0.25 + 0.30 + 0.50 + 0.20 + 0.05
๐ธ = 1.30
โ๏ธ Final:
1.3 kg
๐ โ 8. Pinto supplies 3.79 L, 4.2 L, and 4.25 L of milk in the first three days. In 6 days, he supplies 25 L of milk. Find the quantity supplied in the last three days.
๐ โ Answer:
๐น Milk supplied in first three days:
๐ธ 3.79 + 4.20 + 4.25 = 12.24
๐น Milk supplied in last three days:
๐ธ 25 โ 12.24 = 12.76
โ๏ธ Final:
12.76 L
๐ โ 9. Tinku weighed 35.75 kg in January and 34.50 kg in February. Has he gained or lost weight? How much is the change?
๐ โ Answer (Teacher-like explanation):
๐น January weight = 35.75 kg
๐น February weight = 34.50 kg
๐น To find the change, subtract February weight from January weight.
๐ธ 35.75 โ 34.50 = 1.25
๐น Since the weight has decreased, Tinku has lost weight.
โ๏ธ Final:
Tinku has lost 1.25 kg.
๐ โ Q10. Extend the pattern:
5.5, 6.4, 6.39, 7.29, 7.28, 6.18, 6.17, ___, ___
๐ โ Answer (Teacher-like, step-by-step explanation):
๐น First, observe that the numbers come in pairs.
๐น Write the numbers pair-wise to see the pattern clearly:
๐ธ (6.4, 6.39)
๐ธ (7.29, 7.28)
๐ธ (6.18, 6.17)
๐น In each pair, the second number is 0.01 less than the first.
๐น Now focus only on the first numbers of each pair:
๐ธ 6.4
๐ธ 7.29
๐ธ 6.18
๐น Notice the change:
- 6.4 โ 7.29 (+0.89)
- 7.29 โ 6.18 (โ1.11)
๐น This increase and decrease happens alternately.
๐น Since the last first-number was 6.18, the next first-number will be:
๐ธ 6.18 โ 1.11 = 5.07
๐น Following the pair rule, the next number will be:
๐ธ 5.07 โ 0.01 = 5.06
โ๏ธ Final:
๐ โ
5.07, 5.06
๐ โ 11. How many millimeters make 1 kilometer?
๐ โ Answer (Teacher-like explanation):
๐น 1 kilometer = 1000 meters
๐น 1 meter = 1000 millimeters
๐น Multiply:
๐ธ 1000 ร 1000 = 1,000,000
โ๏ธ Final:
1 kilometer = 1,000,000 millimeters
๐ โ 12. Indian Railways offers optional travel insurance costing 45 paise per passenger. If 1 lakh people opt for insurance in a day, what is the total insurance fee paid?
๐ โ Answer (Teacher-like explanation):
๐น Cost per passenger = 45 paise
๐น 1 lakh people = 100,000 people
๐น Total cost in paise:
๐ธ 100,000 ร 45 = 4,500,000 paise
๐น Convert paise to rupees
๐ธ 100 paise = 1 rupee
๐ธ 4,500,000 รท 100 = 45,000
โ๏ธ Final:
The total insurance fee paid is โน45,000.
๐ โ 13. Which is greater?
๐ โ (a) 10/1000 or 1/10 ?
๐ โ Answer:
๐น Convert both to decimals.
๐ธ 10/1000 = 0.01
๐ธ 1/10 = 0.1
โ๏ธ Final:
1/10 is greater.
๐ โ (b) One-hundredth or 90 thousandths?
๐ โ Answer:
๐น One-hundredth = 1/100 = 0.01
๐น 90 thousandths = 90/1000 = 0.09
โ๏ธ Final:
90 thousandths is greater.
๐ โ (c) One-thousandth or 90 hundredths?
๐ โ Answer:
๐น One-thousandth = 1/1000 = 0.001
๐น 90 hundredths = 90/100 = 0.90
โ๏ธ Final:
90 hundredths is greater.
๐ โ 14. Write the decimal forms of the quantities mentioned:
๐ โ (a) 87 ones, 5 tenths and 60 hundredths
๐ โ Answer:
โ๏ธ Final:
88.10
๐ โ (b) 12 tens and 12 tenths
๐ โ Answer (Teacher-like explanation):
๐น 12 tens = 120
๐น 12 tenths = 1.2
โ๏ธ Final:
121.2
๐ โ (c) 10 tens, 10 ones, 10 tenths, and 10 hundredths
๐ โ Answer:
๐น 10 tens = 100
๐น 10 ones = 10
๐น 10 tenths = 1
๐น 10 hundredths = 0.10
โ๏ธ Final:
111.10
๐ โ (d) 25 tens, 25 ones, 25 tenths, and 25 hundredths
๐ โ Answer:
๐น 25 tens = 250
๐น 25 ones = 25
๐น 25 tenths = 2.5
๐น 25 hundredths = 0.25
โ๏ธ Final:
277.75
๐ โ 15. Using each digit 0โ9 not more than once, fill the boxes so that the sum is closest to 10.5
๐ โ Answer (Teacher-like explanation):
๐น One possible arrangement close to 10.5 is:
๐ธ 5.26
๐ธ 5.24
๐น Sum = 10.50
โ๏ธ Final:
A correct arrangement gives a sum of 10.5.
๐ โ 16. Write the following fractions in decimal form:
๐ โ (a) 1/2
๐ โ
Answer:
0.5
๐ โ (b) 3/2
๐ โ
Answer:
1.5
๐ โ (c) 1/4
๐ โ
Answer:
0.25
๐ โ (d) 3/4
๐ โ
Answer:
0.75
๐ โ (e) 1/5
๐ โ
Answer:
0.2
๐ โ (f) 4/5
๐ โ
Answer:
0.8
——————————————————————————————————————————————————————————————————————————–
OTHER IMPORTANT QUESTIONS
( MODEL QUESTION PAPER )
ESPECIALLY MADE FOR THIS LESSON ONLY
๐ต Section A โ Very Short Answer (1 ร 6 = 6 marks)
๐ โ Question 1
What is a decimal number?
๐ โ
Answer:
๐น A decimal number is a number that has a decimal point
๐น It shows parts of a whole
๐ โ Question 2
Write one decimal number between 2 and 3.
๐ โ
Answer:
๐น One decimal number between 2 and 3 is 2.5
๐ โ Question 3
How many tenths make one whole?
๐ โ
Answer:
๐น Ten tenths make one whole
๐ โ Question 4
What is the place value of 4 in 3.47?
๐ โ
Answer:
๐น The digit 4 is in the tenths place
๐ โ Question 5
True or False: 2.5 = 2.50
๐ โ
Answer:
๐น True
๐ โ Question 6
Which is greater: 0.6 or 0.56?
๐ โ
Answer:
๐น Write both with same decimal places: 0.60 and 0.56
๐น 0.60 is greater
๐ข Section B โ Short Answer I (2 ร 6 = 12 marks)
๐ โ Question 7
Write the place value of each digit in 4.305.
๐ โ
Answer:
๐น 4 is in the ones place
๐น 3 is in the tenths place
๐น 0 is in the hundredths place
๐น 5 is in the thousandths place
๐ โ Question 8
Write 3.7 in words.
๐ โ
Answer:
๐น Three point seven
๐ โ Question 9
Compare 5.2 and 5.18.
๐ โ
Answer:
๐น Write both with same decimal places: 5.20 and 5.18
๐น 5.20 is greater
๐น So 5.2 > 5.18
๐ โ Question 10
Write any two decimal numbers between 1.2 and 1.3.
๐ โ
Answer:
๐น 1.21
๐น 1.25
๐ โ Question 11
Why are zeros added after a decimal number?
๐ โ
Answer:
๐น Zeros do not change the value of a decimal number
๐น They help in comparison and calculation
๐ โ Question 12
Write the decimal form of five tenths.
๐ โ
Answer:
๐น Five tenths = 0.5
๐ก Section C โ Short Answer II (3 ร 10 = 30 marks)
๐ โ Question 13
Write the number name of 2.406.
๐ โ
Answer:
๐น Two point four zero six
๐ โ Question 14
Compare 3.75 and 3.705 using place value.
๐ โ
Answer:
๐น Write both with same decimal places: 3.750 and 3.705
๐น Compare hundredths place: 5 > 0
๐น So 3.75 is greater
๐ โ Question 15
Write three decimal numbers between 4.2 and 4.3.
๐ โ
Answer:
๐น 4.21
๐น 4.25
๐น 4.29
๐ โ Question 16
Explain the meaning of tenths and hundredths.
๐ โ
Answer:
๐น Tenths represent one part out of ten equal parts
๐น Hundredths represent one part out of one hundred equal parts
๐ โ Question 17
Arrange 1.45, 1.5, and 1.405 in ascending order.
๐ โ
Answer:
๐น Write with same decimal places: 1.450, 1.500, 1.405
๐น Ascending order
๐น 1.405 < 1.45 < 1.5
๐ โ Question 18
Write the expanded form of 3.204.
๐ โ
Answer:
๐น 3 + 2/10 + 0/100 + 4/1000
๐ โ Question 19
Explain how decimal numbers are useful in daily life.
๐ โ
Answer:
๐น Used in money
๐น Used in measurement of length and weight
๐น Used in time calculation
๐ โ Question 20
Write two decimal numbers equal to 6.3.
๐ โ
Answer:
๐น 6.30
๐น 6.300
๐ โ Question 21
What is the successor of 2.99?
๐ โ
Answer:
๐น One successor of 2.99 is 3.00
๐ โ Question 22
Explain how decimals are shown on a number line.
๐ โ
Answer:
๐น Divide the space between two whole numbers into equal parts
๐น Each part represents tenths or hundredths
๐ด Section D โ Long Answer (4 ร 8 = 32 marks)
๐ โ Question 23
Explain place value in decimal numbers with an example.
๐ โ
Answer:
๐น Digits to the right of the decimal point have place values like tenths and hundredths
๐น Example: In 4.36
๐น 3 is in the tenths place
๐น 6 is in the hundredths place
๐ โ Question 24
Compare 7.08 and 7.8 and explain the steps.
๐ โ
Answer:
๐น Write both with same decimal places: 7.08 and 7.80
๐น Compare tenths place: 0 < 8
๐น So 7.8 is greater
๐ โ Question 25
Write five decimal numbers between 2.4 and 2.5.
๐ โ
Answer:
๐น 2.41
๐น 2.42
๐น 2.43
๐น 2.44
๐น 2.45
๐ โ Question 26
Explain the use of zeros in decimal numbers with examples.
๐ โ
Answer:
๐น Zeros added after the decimal do not change value
๐น Example: 5.6 = 5.60 = 5.600
๐ โ Question 27
Show 3.6 on the number line (explain in words).
๐ โ
Answer:
๐น Take the interval between 3 and 4
๐น Divide it into ten equal parts
๐น The sixth part from 3 represents 3.6
๐ โ Question 28
Arrange 4.125, 4.12, and 4.205 in descending order.
๐ โ
Answer:
๐น Write with same decimal places: 4.125, 4.120, 4.205
๐น Descending order
๐น 4.205 > 4.125 > 4.12
๐ โ Question 29
Explain any four common mistakes while working with decimal numbers.
๐ โ
Answer:
๐น Ignoring place value
๐น Comparing without aligning decimal points
๐น Misreading decimals
๐น Thinking 2.5 is smaller than 2.35
๐ โ Question 30
Explain the importance of decimal numbers in daily life.
๐ โ
Answer:
๐น Used in money transactions
๐น Used in measurements
๐น Used in science and data
๐น Helps in accurate calculation
——————————————————————————————————————————————————————————————————————————–