Subtracting 9s shortcut

Discussion in 'Calculator Requests' started by math_celebrity, Dec 10, 2023.

Tags:
  1. math_celebrity

    math_celebrity Administrator Staff Member

    Subtracting 9s shortcut

    Add the digits of the larger number
    • 10 - 9 = 1 + 0 = 1
    • 11 - 9 = 1 + 1 = 2
    • 12 - 9 = 1 + 2 = 3
    • 13 - 9 = 1 + 3 = 4
    • 14 - 9 = 1 + 4= 5
    • 15 - 9=. 1 + 5 = 6
    • 16 - 9 = 1 + 6= 7
    • 17 - 9= 1 + 7 = 8
    • 18 - 9 = 1 + 8 = 9
    • 19 - 9 = 1 + 9 = 10
     
    math_celebrity, Dec 10, 2023
    #1

Share This Page