How to multiply and divide by 0, 1, 10 and 100

Multiplying by 1, 10, or 100

  • When you multiply by 1 the answer stays the same. 21 × 1 = 21
  • When you multiply by 10, move all the digits one place to the left, putting a zero in the empty space. 21 × 10 = 210
  • When you multiply by 100, move all the digits two places to the left, putting a zero in the empty spaces. 21 × 100 = 2100
21 × 10 multiplication written on paper
21 × 10 = 210

Any number multiplied by 0 is 0

  • 5 × 0 = 0
  • 100 × 0 = 0
  • 9456 × 0 = 0
  • What is 1,000,000 × 0?
A rectangle character looking confused at the sum 9456 x 0 = 0

Dividing by 1, 10 or 100

  • When you divide by 1 the answer stays the same. 21 ÷ 1 = 21
  • When you divide by 10, move all the digits one place to the right. 210 ÷ 10 = 21
  • When you divide by 100, move all the digits two places to the right. 2100 ÷ 100 = 21
210 divided by 10 written on grid paper.
210 ÷ 10 = 21