BEATCALC:  Beat the Calculator!

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Back to Calculation Tips & Tricks
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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



  Reversing/adding/subtracting 3-digit numbers

  1. Select a number with different 1st and 3rd digits.
  2. Reverse the digits.
  3. Subtract the smaller digit from the larger.
  4. Reverse the digits of this answer.
  5. Add these two numbers.
  6. Subtract a number from this sum.
  7. The final answer will be 1089 minus whatever number you choose in step 6!

   Example:

  1. For the last step you say to subtract 22.
  2. The answer is: 1089 - 22 = 1067.

   See the pattern?

  1. For the last step you say to subtract 101.
  2. The answer is: 1089 - 101 = 988.

Each time, change the number you select for the last step - just select one that is easy to subtract from 1089. Then your answers will be immediate and correct.


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24 February 1997
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