1. Choose a number (start with 2 digits and advance to 3 with practice).
2. Divide by 4 (or divide twice by 2).
3. Move the decimal point one place to the left.
Example:
1. If the number selected is 86:
2. Divide 86 by 4: 86/4 = 21.5
3. Move the decimal point one place to the left.: 2.15
4. So 2 1/2% of 86 = 2.15.
See the pattern?
1. If the number selected is 648:
2. Divide 648 by 2 twice: 648/2 = 324, 324/2 = 162
3. Move the decimal point one place to the left.: 16.2
4. So 2 1/2% of 648 = 16.2.
Practice dividing by 4, or by 2 twice, and you will be able to find these answers faster than with a calculator.
Finding 5 percent of a number
1. Choose a large number (or sum of money).
2. Move the decimal point one place to the left.
3. Divide by 2 (take half of it).
Example:
1. If the amount of money selected is $850:
2. Move the decimal point one place to the left.: 85
3. Divide by 2: 85/2 = 42.50
4. So 5% of $850 = $42.50.
See the pattern?
1. If the amount of money selected is $4500:
2. Move the decimal point one place to the left.: 450
3. Divide by 2: 450/2 = 225
4. So 5% of $4500 = $225.