BEATCALC:  Beat the Calculator!

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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 2 3/4

  1. Multiply the number by 11. Add the digits from right to left.
  2. Divide by 4.

   Example:

  1. If the number chosen to multiply by 2 3/4 is 78:
  2. Multiply by 11. Add digits from right to left: _ _ 8
    8 + 7 = 15
    7 + 1 (carry) = 8
    78 * 11 = 858
  3. Divide by 4: 858/4 = 214 1/2
  4. So 78 x 2 3/4 = 214 1/2.

   See the pattern?

  1. If the number to be multiplied by 2 3/4 is 27:
  2. Multiply by 11: 11 x 27 = 297
  3. Divide by 4: 297/4 = 74 1/4
  4. So 27 x 2 3/4 = 74 1/4.


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19 April 1999
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