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MENTAL MATH TRICKS

Are you ready to become do tough math calculations in your head? These Mental Math Tricks will give you the edge and help you become a human calculator!



Squaring a 2-digit number ending in 1

  • Take a 2-digit number ending in 1.
  • Subtract 1 from the number.
  • Square the difference.
  • Add the difference twice to its square.
  • Add 1.

Example:

  1. If the number is 61, subtract 1: 61 - 1 = 60.
  2. 60 × 60 = 3600 (square the difference).
  3. 3600 + 60 + 60 = 3720 (add the difference twice to its square).
  4. 3720 + 1 = 3721 (add 1).
  5. So 61 × 61 = 3721.
Pretty Cool Huh? Mental math shortcuts can benefit students in elementary, middle, high school and beyond!

Here's another:

1. For 81 × 81, subtract 1: 81 - 1 = 80. 2. 80 × 80 = 6400 (square the difference). 3. 6400 + 80 + 80 = 6560 (add the difference twice to its square). 4. 6560 + 1 = 6561 (add 1) 5. So 81 × 81 = 6561.

Multiplying by 111


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