NCERT Solutions for Class 7th Maths Chapter 4 In-text Questions — Decimal Multiplication
Book page 71 Updated on2026-09-19
Q1.
Math Talk: Suppose we know that 596 × 248 = 147808, can you immediately write down the product of 5.96 × 24.8?
Answer
Yes — the answer is 147.808.
596 × 248 = 147808
5.96 has 2 decimal places
24.8 has 1 decimal place
2 + 1 = 3 decimal places in the product
So 5.96 × 24.8 = 147.808
The digits never change — only where the point sits.
Why it happens: 5.96 = 596/100 and 24.8 = 248/10. Multiplying gives (596 × 248) / (100 × 10) = 147808/1000. The numerator is the counting-number product you already know, and the denominator has 2 + 1 = 3 zeroes, so the point moves 3 places left.
Q2.
By looking at the above examples, can you frame a rule to multiply two decimals?
Answer
Rule: remove the decimal points, multiply the two numbers as counting numbers, then put a point in the product so that it has as many decimal places as the two numbers had together.
Step 1: drop the points and multiply. Step 2: count the decimal places in the multiplier and in the multiplicand. Step 3: add those two counts. Step 4: place the point in the product so it has that many digits after it (pad with zeroes in front if needed).
Multiplying decimals is the same as multiplying their fractions.
The product of the numerators is the product of the numbers with the points removed.
Both denominators are 1 followed by zeroes, so their product is also 1 followed by zeroes — and the zeroes add up.
The number of zeroes in the denominator is the number of digits after the point. So the decimal places add up too.
Tip: if the product has fewer digits than the places you need, write zeroes in front. 0.018 × 0.012 needs 6 places, but 18 × 12 = 216 has only 3 digits, so the answer is 0.000216.