## BEATCALC:  Beat the Calculator!

Back to Calculation Tips & Tricks

 From B. Lee Clay

Squaring Numbers

Multiplying Numbers

Dividing Numbers

Subtracting Numbers

Finding Percents

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### Multiplying a 2-digit number by 3 2/3

1. Select a 2-digit number.
2. Multiply the number by 11 (see examples).
3. Divide by 3.

#### Example:

1. The 2-digit number chosen to multiply by 3 2/3 is 34.
2. Multiply by 11 - add digits right to left:
the right digit is 4
the middle digit is 3 + 4 = 7
the left digit is 3
the product is 374.
3. Divide by 3: 374/3 = 124 2/3
4. So 34 × 3 2/3 = 124 2/3.

See the pattern?

1. The 2-digit number chosen to multiply by 3 2/3 is 73.
2. Multiply by 11 - add digits right to left:
the right digit is 3
the middle digit is 3 + 7 = 10; use 0, carry 1
the left digit is 7 + 1 = 8
the product is 803.
3. Divide by 3: 803/3 = 267 2/3
4. So 73 × 3 2/3 = 267 2/3.
Practice multiplying by 11, and you will soon be giving these answers quickly.