Multiplication of Decimals with Whole Numbers
When multiplying decimals by whole numbers, ignore the decimal point at first and multiply as if the numbers are whole numbers. After multiplying, place the decimal point in the answer.
Steps:
- Ignore the decimal point and multiply.
- Count the number of decimal places.
- Place the decimal point correctly in the final answer.
Example 1.30(a)
Solution:
Ignore the decimal point and multiply:
3563 × 14 = 49 882
There are 3 decimal places in 3.563.
Place the decimal point accordingly:
49.882
Example 1.30(b)
Solution:
Ignore the decimal points and multiply:
4425 × 32 = 141 600
Total decimal places = 3.
Place the decimal point:
141.6
Example 1.31(a)
Solution:
Divide 15.6 by 6:
156 ÷ 6 = 26
Place the decimal point in the answer: 2.6
Example 1.31(b)
Solution:
Make the divisor a whole number by multiplying both numbers by 100:
30.78 ÷ 2.28 = 3078 ÷ 228
Divide:
3078 ÷ 228 = 13.5