Finger Math: 9X Rule

 

To multiply by 9,try this:
(1) Spread your two hands out and place them on a desk or table in front of you.
(2) To multiply by 3, fold down the 3rd finger from the left. To multiply by 4, it would be the 4th finger and so on.
(3) the answer is 27 … READ it from the two fingers on the left of the folded down finger and the 7 fingers on the right of it.

This works for anything up to 9×10!

Square a 2 Digit Number Ending in 5


For this example we will use 25

  • Take the “tens” part of the number (the 2 and add 1)=3
  • Multiply the original “tens” part of the number by the new number (2×3)

Take the result (2×3=6) and put 25 behind it. Result the answer 625.

Try a few more 75 squared … = 7×8=56 … put 25 behind it is 5625.
55 squared = 5×6=30 … put 25 behind it … is 3025. Another easy one! Practice it on paper first!

 

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