BEATCALC:  Beat the Calculator!

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Back to Calculation Tips & Tricks
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From the BEATCALC mailing list:
a weekly service from B. Lee Clay, archived here by the Math Forum.
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   Dividing a 2-digit number by 1 1/4

  1. Select a 2-digit number.
  2. Multiply by 8.
  3. Move the decimal point one place to the left.

   Example:

  1. The 2-digit number chosen to divide by 1 1/4 is 32.
  2. Multiply by 8: 8 x 32 = 240 + 16 = 256
  3. Move the decimal point one place to the left: 25.6
  4. So 32 divided by 1 1/4 = 25.6.

   See the pattern?

  1. The 2-digit number chosen to divide by 1 1/4 is 64.
  2. Multiply by 8: 8 x 64 = 480 + 32 = 512
  3. Move the decimal point one place to the left: 51.2
  4. So 64 divided by 1 1/4 = 51.2.

Multiply from left to right for ease and accuracy. You will soon be doing this division by a mixed number quickly.


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6 July 1998
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