Different ways for multiplication

Another way to multiply just over 100

• 103 x 104 = 10712 The answer is in two parts: 107 and 12,
  107 is just 103 + 4 (or 104 + 3),
  and 12 is just 3 x 4.
• Similarly 107 x 106 = 11342 107 + 6 = 113 and 7 x 6 = 42
• Method for multiplying numbers where the first figures are the same and the last figures add up to 10.
  
  • 32 x 38 = 1216 Both numbers here start with 3 and the last
    figures (2 and 8) add up to 10.
    So we just multiply 3 by 4 (the next number up)
    to get 12 for the first part of the answer.
    And we multiply the last figures: 2 x 8 = 16 to
    get the last part of the answer.
    Diagrammatically:
    
  • And 81 x 89 = 7209
  
  
  • Multiplying a number by 11.
  • To multiply any 2-figure number by 11 we just put the total of the two figures between the 2 figures.
    • 26 x 11 = 286 Notice that the outer figures in 286 are the 26
      being multiplied.
      And the middle figure is just 2 and 6 added up.
    • So 72 x 11 = 792