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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   Squaring special numbers (5 and
                 repeating 6's)

  1. Choose a number with a 5 and repeating 6's.
  2. The square is made up of:
    • first digits: 32 & two fewer 1's than repeating 6's
    • next digits: 03 & one fewer 5 than repeating 6's
    • last digit: 6

   Example:

  1. If the number to be squared is 5666:
  2. The square has:

    first digits: 32 and two fewer
        1's than 6's                 3 2 1
    next digits: 03 and one fewer
        5 than 6's                        0 3 5 5
    last digit: 6                                 6

  3. So 5666 x 5666 = 32,103,556.

   See the pattern?

  1. If the number to be squared is 566666:
  2. The square has:

    first digits: 32 and two fewer
       1's than 6's           3 2 1 1 1
    next digits: 03 and one fewer
       1 than 6's                      0 3 5 5 5 5
    last digit: 6                                  6

  3. So 566666 x 566666 = 321,110,355,556.
     


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23 August 1999
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