Multiplication of decimals by a whole number

Multiplying by powers of 10

When any number is multiplied by a power of 10, each digit is multiplied by the same power of 10. For example:

24.06 × 10	= 20 × 10 + 4 × 10 + 0.06 × 10
	= 200 + 40 + 0.6 = 240.6.

• Multiplying by 10 corresponds to moving the decimal point one place to the right and inserting a zero where necessary.

• Similarly multiplying by 100 = 10² corresponds to moving the decimal point two places to the right and inserting zeros where necessary. For example:
  8.7 × 100 = 870.

• Multiplying by 1000 = 10³ corresponds to moving the decimal point three places to the right and inserting zeros where necessary. For example:
  8.7 × 1000 = 8700.

Question 3

Complete each of the following multiplications:

a	32.4 × 10
b	56.897 × 100
c	978.09 ×1000

Question 2

Multiplying whole numbers by decimals