NCERT 5th Class (CBSE) Mathematics: Decimals

Comparing Decimal

Adding and subtracting Decimals

Adding and subtracting decimal numbers is just like adding and subtracting whole numbers. Remember to line up the decimal points one below the other. Change to like decimals if required.

(a) 5.32+3.8

5.32+3.8 = 9.12

(b) 0.96+1.2

0.96+1.2 = 2.16

(c) 2.1-0.87

2.1-0.87 = 1.23

(d) 1-0.4

1.00-0.4 = 0.58

MULTIPLICATION OF DECIMALS

A. Multiplying Decimals by a Whole Number

(a) A greeting card costs Rs 8.25. If Shabnam buys three cards, how much should she pay the shopkeeper?

8.25+8.25+8.25 = ?

or

3 × 8.25 = ?

Step 1. Multiply as with whole numbers ignoring the decimal.

8.25×3 = 2475

Step 2. Count the number of decimal places in the factors.

8.25 (2 decimal places) × 3 (0 decimal place) = 2475

Step 3. Show the number of decimal places in the product.

8.25×3 = 24.75 ( 2+0 = 2 decimal places inn all)

Answer: Shabnam has to pay Rs 24.75.

(b) 4.5×16 = 720 → 4.5×16 = 72.0

(c) 0.09×24 = 216 →  0.09×24 = 2.16