Can you carry out the same addition using decimal notation? It is shown below. Share your observations. 2 ⁷⁄₁₀ + 3 ⁵⁄₁₀ = 5 ¹²⁄₁₀ = 6 ²⁄₁₀ 1 2.7 + 3.5 = 6.2 Page 74 — the same sum 2 ⁷⁄₁₀ + 3 ⁵⁄₁₀ worked in fraction form (left) and in decimal notation (right).

Yes. Here are the two forms side by side. Fraction form Decimal form 2 7 &frasl; 10 + 3 5 &frasl; 10 2.7 + 3.5 = 5 12 &frasl; 10 carry 1 from the tenths column = 6 2 &frasl; 10 = 6.2 Observations: The steps are identical; only the way of writing changes. In decimal form the decimal points must be lined up one below the other — that is what keeps tenths under tenths. The carry "1" above the units column stands for the whole unit made by 10 tenths. The standard column method for whole numbers works unchanged for decimals. Why it happens: decimal notation is only a shorter way of recording place values. Since the places behave the same, the arithmetic rules must behave the same too.

NCERT Solutions for Class 7th Maths Chapter 3 In-text Questions — Addition and Subtraction of Decimals

Book page 74 Updated on2026-09-19

Q1.

Priya requires 2.7 m of cloth for her skirt, and Shylaja requires 3.5m for her kurti. What is the total quantity of cloth needed?

Answer

2.7 + 3.5
Tenths: 7 + 5 = 12 tenths = 1 unit and 2 tenths
Units: 2 + 3 + 1 (carried) = 6
Total = 6.2 m

In fraction form the same sum reads:

2 ⁷⁄₁₀ + 3 ⁵⁄₁₀ = 5 ¹²⁄₁₀ = 6 ²⁄₁₀

Why it happens: the carry from the tenths column into the units column is exactly the "10 tenths = 1 unit" exchange, written in the short decimal form.

Tip: in the shop this would be about 6 metres and 20 centimetres of cloth.

Q2.

Can you carry out the same addition using decimal notation? It is shown below. Share your observations.

Page 74 — the same sum 2 ⁷⁄₁₀ + 3 ⁵⁄₁₀ worked in fraction form (left) and in decimal notation (right).

Answer

Yes. Here are the two forms side by side.

Fraction form	Decimal form
2 ⁷⁄₁₀ + 3 ⁵⁄₁₀	2.7 + 3.5
= 5 ¹²⁄₁₀	carry 1 from the tenths column
= 6 ²⁄₁₀	= 6.2

Observations:

The steps are identical; only the way of writing changes.
In decimal form the decimal points must be lined up one below the other — that is what keeps tenths under tenths.
The carry "1" above the units column stands for the whole unit made by 10 tenths.
The standard column method for whole numbers works unchanged for decimals.

Why it happens: decimal notation is only a shorter way of recording place values. Since the places behave the same, the arithmetic rules must behave the same too.

Q3.

How much longer is Shylaja’s cloth compared to Priya’s?

Answer

3.5 – 2.7
7 tenths cannot be taken from 5 tenths, so borrow 1 unit:
3.5 = 2 units and 15 tenths
Tenths: 15 – 7 = 8
Units: 2 – 2 = 0
= 0.8 m

In fraction form: 3 ⁵⁄₁₀ – 2 ⁷⁄₁₀ = 2 ¹⁵⁄₁₀ – 2 ⁷⁄₁₀ = ⁸⁄₁₀.

Why it happens: borrowing across the decimal point is the ordinary borrowing rule — one unit becomes ten tenths, just as one ten becomes ten ones.

Check it yourself: 2.7 + 0.8 = 3.5 ✓ So Shylaja needs 0.8 m — that is 80 cm — more cloth than Priya.

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