## 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 4's number by 55

1. Choose a repeating 4's number (4444, etc.)
2. Multiply it by 55
3. The product is:
- the first digit is 2
- the next digits are repeating 4's (one fewer than repeating 4's in the original number)
- the last two digits are 20

#### Example:

1. If the first number is 4444:
2. First digit is 2.
3. Next are repeating 4 digits -- one fewer than repeating 4's in the original number: 444.
4. Last two digits are 20.
5. So 55 × 4444 = 244420.

See the pattern?

1. Next pick is 444444:
2. First digit is 2.
3. Next are repeating 4 digits -- one fewer than repeating 4's in the original number: 44444.
4. Last two digits are 20.
5. So 55 × 444444 = 24444420.

You can see that following these three steps will enable you to give these large products quickly.