## BEATCALC:  Beat the Calculator!

Back to Calculation Tips & Tricks

 From B. Lee Clay

Squaring Numbers

Multiplying Numbers

Dividing Numbers

Subtracting Numbers

Finding Percents

Calculation
Practice Exercises

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### Multiplying two mixed numbers

1. Select a mixed number. (1 2/3, 5 1/8, etc.)
2. Select a multiplier using the same whole number and a fraction that sums to 1 with the first number's fractional part.
3. The whole number in the answer will be the whole number times the next number.
4. To find the fraction, multiply the two fractional parts.

#### Example:

1. The first mixed number chosen is 7 1/4.
2. Select 7 3/4 as the multiplier (same whole number,
fraction that sums to 1 with the first fraction.
3. The product's whole number will be 7 × 8 (next number) = 56.
4. The product's fraction will be 1/4 × 3/4 = 3/16.
5. So 7 1/4 × 7 3/4 = 56 3/16.

See the pattern?

1. The first mixed number chosen is 8 1/3.
2. Select 8 2/3 as the multiplier (same whole number,
fraction that sums to 1 with the first fraction.
3. The product's whole number will be 8 × 9 (next number) = 72.
4. The product's fraction will be 1/3 × 2/3 = 2/9.
5. So 8 1/3 × 8 2/3 = 72 2/9.

#### One more:

1. The first mixed number chosen is 20 1/8.
2. Select 20 7/8 as the multiplier (same whole number,
fraction that sums to 1 with the first fraction.
3. The product's whole number will be 20 × 21 (next number) = 420.
4. The product's fraction will be 1/8 × 7/8 = 7/64.
5. So 20 1/8 × 20 7/8 = 420 7/64.