## BEATCALC:  Beat the Calculator!

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 From B. Lee Clay

Squaring Numbers

Multiplying Numbers

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### Multiplying a repeating 9's number by 22

1. Choose a repeating 9's number (e.g., 9999).
2. The product is made up of:
- first two digits are 21.
- next digits are repeating 9's -- two fewer than repeating 9's in original number.
- last two digits are 78.

#### Example:

1. The repeating 9's number chosen to multiply by 22 is 9999.
2. First two digits are 21.
3. Next digits are repeating 9's -- two fewer than repeating 9's in original number: 99.
4. Last two digits are 78.
5. So 22 × 9999 is 219978.

See the pattern?

1. The repeating 9's number chosen to multiply by 22 is 9999999.
2. First two digits are 21.
3. Next digits are repeating 9's -- two fewer than repeating 9's in original number: 99999.
4. Last two digits are 78.
5. So 22 × 9999999 is 219999978.
Use these three steps to impress your friends with your mental multiplying of BIG numbers.