BEATCALC:  Beat the Calculator!

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Back to Calculation Tips & Tricks
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   Dividing a 2- or 3-digit number by 35

  1. Select a 2-digit number. (Choose larger numbers when you feel sure about the method.)
  2. Multiply by 2.
  3. Divide the resulting number by 7.
  4. Move the decimal point 1 place to the left.

   Example:

  1. If the number chosen to divide by 35 is 61:
  2. Multiply by 2: 2 x 61 = 122.
  3. Divide by 7: 122/7 = 17 3/7
  4. Move the decimal point 1 place to the left: 1.7 3/7
  5. So 61 divided by 35 = 1.7 3/7.

   See the pattern?

  1. If the number chosen to divide by 35 is 44:
  2. Multiply by 2: 2 x 44 = 88
  3. Divide by 7: 88/7 = 12 4/7
  4. Move the decimal point 1 place to the left: 1.2 4/7
  5. So 44 divided by 35 = 1.2 4/7.

Division done by calculator will give repeating decimals (unless the original number is a multiple of 7), truncated by the limits of the display. The exact answer must be expressed as a mixed number.


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2 August 1998
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