## BEATCALC:  Beat the Calculator!

Back to Calculation Tips & Tricks

 From B. Lee Clay

Squaring Numbers

Multiplying Numbers

Dividing Numbers

Subtracting Numbers

Finding Percents

Calculation
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### Multiplying a repeating 2's number by 17

1. Choose a repeating 2's number (222, etc.)
2. Multiply it by 17
3. The product is:
- the first digit is 3
- the next digits are repeating 7's (one fewer than repeating 2's in the original number)
- the last digit is 4

#### Example:

1. If the first number is 22222:
2. Multiply by 17. The product is:
- the first digit is 3: 3.
- the next digits are repeating 7's (one fewer than repeating 2's in the original number): 7777.
- the last digit is 4: 4.
3. So 22222 × 17 = 377774.

See the pattern?

1. If the first number is 222222222:
2. Multiply by 17. The product is:
- the first digit is 3: 3.
- the next digits are repeating 7's (one fewer than repeating 2's in the original number): 77777777.
- the last digit is 4: 4.
3. So 222222222 × 17 = 3777777774.

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29 April 2008
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