## 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 1's number by 41

1. Choose a repeating 1's number (111, etc.)
2. Multiply it by 41
3. The product is:
- first digit is 4
- next digits are 5's - one fewer than repeating 1's in the original number
- last digit is 1.

#### Example:

1. If the first number is 1111:
2. Multiply by 41. The product is:
first digit is 4: 4
next digits are 5's, one fewer than 1's: 555
last digit is 1: 1
3. So 1111 × 41 = 45551.

See the pattern?

1. If the first number is 111111:
2. Multiply by 41. The product is:
first digit is 4: 4
next digits are 5's, one fewer than 1's: 55555
last digit is 1: 1
3. So 11111 × 41 = 4555551.
Use these three steps and amaze your friends with you ability to produce these products.

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23 May 2005
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