Page 35 - Maths Skills - 7

Fractions and Decimals 33

Let’s Attempt

Example 1: Multiply 2.6 and 3.15.
Solution: Step 1. Multiply 315 and 26 (without considering the decimals).
The product is 8190. (315 × 26 = 8190).

Step 2. Count the places of decimals in 3.15 and 2.6, they are 2 and 315
1 respectively.
Find the sum of 2 and 1, which is 2 + 1 = 3. ×26
Step 3. Count three digits of the product from right obtained in Step 1890
1 and put the decimal point. +6300

Thus, the product of 3.15 and 2.6 = 8.190. 8190

Example 2: Find the product.
(i) 16.728 × 2.6 (ii) 628.12 × 1.2

Solution: Multiply the numbers without decimal points.

(i) 16728
×26 Count the number of decimal places and find their sum. This is
100368 3 + 1 = 4. Place decimal after four digits from the right of the
product, i.e., 43.4928.
+334560
434928 Thus, 16.728 × 2.6 = 43.4928.

(ii) 62812 Count 3 places from right and place the decimal point, i.e.,
×12 753.744.
125624
+628120

753744 Thus, 628.12 × 1.2 = 753.744.

DIVISION OF DECIMAL NUMBERS

Case 1. If the divisor is a whole number (≠ 0) and the dividend is a decimal.

Case 2. If the divisor and dividend both are decimals.
Case 3. When the divisor is a decimal and the dividend is a whole number.

Division of a Decimal by 10, 100, 1000, …etc.

For dividing decimals by 10, 100, 1000, we count the number of zeroes in the divisor and decimal point is shifted
to left by as many places as there are zeroes in the divisor.
For example;
176.75 ÷ 100 = 1.7675, (Decimal point is shifted by two places to the left.)

125.46 ÷ 10 = 12.546, (Decimal point is shifted by one place to the left.)