## BEATCALC:  Beat the Calculator!

Back to Calculation Tips & Tricks

 From B. Lee Clay

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### Multiplying a 2-digit number by 4 5/9

1. Select a 2-digit number.
2. Multiply the number by 4.
3. Add one zero.
4. Add the original number.
5. Divide by nine.

#### Example:

1. The 2-digit number chosen to multiply by 4 5/9 is 23.
2. Multiply by 4: 4 × 23 = 80 + 12 = 92
3. Add one zero: 920
4. Add the original number: 920 + 23 = 943
5. Divide by 9: 943/9 = 104 7/9
6. So 23 × 4 5/9 = 104 7/9.

See the pattern?

1. The 2-digit number chosen to multiply by 4 5/9 is 61.
2. Multiply by 4: 4 × 61 = 244
3. Add one zero: 2440
4. Add the original number: 2440 + 61 =
2440 + 60 + 1 = 2550 + 1 = 2501
5. Divide by 9: 2501/9 = 277 8/9
6. So 61 × 4 5/9 = 277 8/9.

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