## 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 2-digit number by 49 1/2

1. Select a 2-digit number.
2. Divide by 2.
3. Subtract this from 50 times the original number.

#### Example:

1. The 2-digit number chosen to multiply by 49 1/2 is 21.
2. Divide by 2: 21/2 = 10 1/2.
3. Subtract this from 50 times the original number: 50(21) - 10 1/2 = 1050 - 10 1/2 = 1040 - 1/2 = 1039 1/2.
4. So 21 × 49 1/2 = 1039 1/2.

See the pattern?

1. If the 2-digit number chosen to multiply by 49 1/2 is 64:
2. Divide by 2: 64/2 = 32.
3. Subtract this from 50 times the original number: 50(64) - 32 = 3200 -32 = 3170 - 2 = 3168.
4. So 64 × 49 1/2 = 3168.
Remember to multiply and subtract from left to right. Then these answers will become easy and accurate.

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15 November 2004
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