BEATCALC:  Beat the Calculator!

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From B. Lee Clay


 Squaring Numbers

 Multiplying Numbers

 Dividing Numbers

 Adding Numbers

  1. even numbers 2 through selected 2-digit evens
  2. digits of square of repeating ones
  3. consecutive odds
  4. consecutive between 2 numbers
  5. sequence from 1 to selected 2-digit number
  6. sequence from 1 to selected 1-digit number and back
  7. sequences in the 10's
  8. sequences in the 20's
  9. sequences in the 30's
  10. sequences in the 40's
  11. sequences in the 50's
  12. sequences in the 60's
  13. sequences in the 70's
  14. sequences in the 80's
  15. series of doubles
  16. series of quadruples
  17. series of 10 numbers

 Subtracting Numbers

  1. 1's repeating, divide by 9, subtract 21
  2. 8's repeating, divide by 9, subtract 10
  3. squares of two numbers
  4. reversing/adding/subtracting 3-digit numbers

 Percents

  1. finding 2.5 percent
  2. finding 5 percent
  3. finding 15 percent
  4. finding 20 percent
  5. finding 25 percent
  6. finding 33 1/3 percent
  7. finding 40 percent
  8. finding 45 percent
  9. finding 55 percent
  10. finding 60 percent
  11. finding 70 percent
  12. finding 75 percent

Calculation
Practice Exercises

Full List



  Subtract from a repeating 8's number, divide
             by 9, subtract 10

  1. Select a number between 2 and 9 digits made up of 8's.
  2. Subtract a number equal to 9 minus the number of digits in the number you have selected.
  3. Divide by 9. The answer will have one less digit than the original number in the series 98765432.
  4. Subtract 10.

   Example:

  1. If the repeating number selected has 4 digits: 8888:
  2. Subtract 5 (9 minus the number of digits) and divide by 9. The answer will be 987 (1 less digit in sequence than the 4 digits in the selected number).
  3. Subtract 10: 987 - 10 = 977.
  4. So (8888-5) / 9 - 10 = 977.

   See the pattern?

  1. If the repeating number selected has 6 digits: 888888:
  2. Subtract 3 (9 minus the number of digits) and divide by 9. The answer will be 98765 (1 less digit in sequence than the 6 digits in the selected number).
  3. Subtract 10: 98765 - 10 = 98755.
  4. So (888888-3) / 9 - 10 = 98755.
Extend this exercise by changing the last number to subtract, producing a multitude of easily answered problems.


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26 August 1996
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