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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   Multiplying a 2-digit number by 125

  1. Select a 2-digit number.
  2. Divide the number by 8.
  3. Move the decimal point 3 places to the right (add three zeros).

   Example:

  1. The 2-digit number chosen to multiply by 125 is 34.
  2. Divide by 8: 34/8 = 4.25
  3. Move the decimal point 3 places to the right: 4250
  4. So 125 x 34 = 4,250.

   See the pattern?

  1. The 2-digit number chosen to multiply by 125 is 78.
  2. Divide by 8: 78/8 = 9.75
  3. Move the decimal point 3 places to the right: 9750
  4. So 125 x 78 = 9,750.


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10 January 2000
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