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Percentage of an Amount
Percentage of an Amount
Year 7 —.
1. What does “percentage of an amount” mean?
It means finding a part of a number based on a percentage. For example, 20% of 50 means 20 out of every 100 parts of 50.
Example:
20% of 50 = 102. The main method
Percentage of an amount formula
P% of A = A × (P ÷ 100)
Example: Find 35% of 200.
200 × (35 ÷ 100) = 200 × 0.35 = 70
3. Quick mental methods
10% method
10% = divide the number by 10.
Example: 10% of 90 = 9
5% method
5% = half of 10%.
Example: 5% of 90 = 4.5
1% method
1% = divide by 100.
Example: 1% of 250 = 2.5
Build percentages using 10%, 5%, 1%
Example: Find 16% of 80.
10% = 8, 5% = 4, 1% = 0.8 → total = 12.8
4. Worked Examples
a) Find 25% of 160.
160 × 0.25 = 40
b) Find 12% of 300.
300 × 0.12 = 36
c) Find 7% of 450 using mental methods.
1% = 4.5 → 7 × 4.5 = 31.5
5. Practice
- Find
20%of80. - Find
15%of120. - Find
8%of250. - Find
60%of70. - Find
4%of600. - Find
33%of90. - Find
75%of200. - Find
1%of540. - Find
12.5%of64. - Find
3%of850.
Answers (teacher)
80 × 0.20 = 16120 × 0.15 = 18250 × 0.08 = 2070 × 0.60 = 42600 × 0.04 = 2490 × 0.33 = 29.7200 × 0.75 = 150540 × 0.01 = 5.464 × 0.125 = 8850 × 0.03 = 25.5