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How to find 2.5 percent of a number?
- Choose a number (start with 2 digits and advance to 3 with practice).
- Divide by 4 (or divide twice by 2).
- Move the decimal point one place to the left.
Example:
- If the number selected is 110:
- Divide 110 by 4: 110/4 = 27.5
- Move the decimal point one place to the left : 2.75
- So, 2.5% of 110 = 2.75.
How to find 5% of a number?
- Choose a large number (or sum of money).
- Move the decimal point one place to the left.
- Divide by 2 (take half of it).
Example:
- If the amount of money selected is Rs.850:
- Move the decimal point one place to the left.: 85
- Divide by 2: 85/2 = 42.50
- So 5% of Rs.850 = Rs.42.50.
How to find 15% of a number?
- Choose a 2-digit number.
- Multiply the number by 3.
- Divide by 2.
- Move the decimal point one place to the left.
Example:
- If the number selected is 43:
- Multiply by 3: 3 × 43 = 129
- Divide by 2: 129/2 = 64.5
- Move the decimal point one place to the left: 6.45
- So 15% of 43 = 6.45
How to find 20 percent of a number?
- Choose a 2-digit number.
- Divide the number by 5.
Example:
- If the number selected is 38:
- Divide by 5: 38/5 = 7.6
- So 20% of 38 = 7.6
How to find 25 percent of a number
- Divide by 4.
Example:
- If the number selected is 86:
- Divide 86 by 4: 86/4 = 21.5
- So 25% of 86 = 21.5.
How to find 33 1/3 percent of a number
- Choose a number.
- Divide the number by 3.
Example:
- If the number selected is 74
- Divide by 3: 74/3 = 24 2/3
- So 33 1/3% of 74 = 24 2/3
How to find 40 percent of a number
- Choose a 2-digit number.
- Multiply the number by 4.
- Move the decimal point one place to the left.
Example:
- If the number selected is 21:
- Multiply by 4: 4 × 21 = 84
- Move the decimal point one place to the left: 8.4.
- So 40% of 21 = 8.4.
How to find 45 percent of a number
- Choose a 2-digit number.
- Multiply the number by 9.
- Divide by 2.
Move the decimal point one place to the left.
Example:
- If the number selected is 36:
- Multiply by 9: 9 × 36 = 270 + 54 = 324
- Divide by 2: 324/2 = 162
- Move the decimal point one place to the left: 16.2
- So 45% of 36 = 16.2.
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