Mental Math Tricks

Ready to become do tough math calculations in your head?  Mental Math Tricks can help give anyone the edge and help you become a human calculator!  See how with a bit of practice, anybody has the ability to perform seemingly difficult math problems without a 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:    61 x 61

  1. Subtract 1:

    61 - 1 = 60

  2. Square the difference:

    60 × 60 = 3600

  3. Add the Difference Twice to its Square:

    3600 + 60 + 60 = 3720

  4. Add 1:

    3720 + 1 = 3721

  5. There you have it!    61 × 61 = 3721
 

Here's another:

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.

Pretty Cool Huh?  Mental math shortcuts can benefit students in elementary, middle, high school and beyond!  One of the best things is that anyone can learn mental math.  it just takes some practice....


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