## 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

Full List

### Multiplying a 2-digit number by 4.3

1. Multiply the number by 3.
2. Move decimal one place left.
3. Add this to 4 times original number.

#### Example:

1. The 2-digit number chosen to multiply by 4.3 is 21.
2. Multiply by 3: 3 × 21 = 63.
3. Move decimal one place left: 6.3.
4. Add to 4 times original number: 6.3 + 4(21) = 6.3 + 84 = 90.3.
5. So 4.3 × 21 is 90.3.

See the pattern?

1. The 2-digit number chosen to multiply by 4.3 is 62.
2. Multiply by 3: 3 × 62 = 186.
3. Move decimal one place left: 18.6.
4. Add to 4 times original number: 18.6 + 4(62) = 18.6 + 240 + 8 = 18.6 + 248 = 258 + 8.6 = 266.6
5. So 4.3 × 62 is 266.6.
Remember to multiply and add left to right and these problems will become easy. In not time you will be giving these answers quickly using mental math.