## BEATCALC:  Beat the Calculator!

Back to Calculation Tips & Tricks

 From B. Lee Clay

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### Multiplying a 2-digit number by 2.6

1. Multiply the number by 6.
2. Move decimal one place left.
3. Add this to 2 times original number.

#### Example:

1. The 2-digit number chosen to multiply by 2.6 is 21.
2. Multiply by 6: 6 × 21 = 126.
3. Move decimal one place left: 12.6.
4. Add to 2 times original number: 12.6 + 2(21) = 12.6 + 42 = 54.6.
5. So 2.6 × 21 is 54.6.

See the pattern?

1. The 2-digit number chosen to multiply by 2.6 is 37.
2. Multiply by 6: 6 × 37 = 180 + 42 = 222.
3. Move decimal one place left: 22.2.
4. Add to 2 times original number: 22.2 + 2(37) = 22.2 + 60 + 14 = 82.2 + 14 = 96.2.
5. So 2.6 × 37 is 96.2.
Multiply and add left to right and you will be able to give these answers quickly and accurately.

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19 September 2005
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