A jacket costs $120 and is on sale for 25% off. How much is the discount?
A$3
B$25
C$30
D$95
25% of $120 = 0.25 × $120 = $30. The discount is $30, making the sale price $90. A common error is multiplying without the decimal conversion (25 × 120 = 3,000 ÷ 100 is one corrective path) or subtracting 25 directly from 120.
Question 2 True / False
To find 40% of 70, you should divide 70 by 40.
TTrue
FFalse
Answer: False
The phrase 'percent of' means multiply, not divide. 40% of 70 = 0.40 × 70 = 28. Dividing gives 70 ÷ 40 = 1.75, which is unrelated. This is the most common error with this skill: 'of' is the mathematical signal for multiplication.
Question 3 Short Answer
What are the three steps to find any percent of a number, and why is the decimal conversion step necessary?
Think about your answer, then reveal below.
Model answer: Step 1: Convert the percent to a decimal by dividing by 100 (e.g., 35% → 0.35). Step 2: Multiply the decimal by the number. Step 3: Interpret the result in context. The conversion is necessary because percent means 'per hundred' — without it, multiplying 35 × 80 gives 2,800, which is 100 times too large.
The decimal conversion makes the meaning of 'per hundred' explicit in the arithmetic. Writing 35% as 35/100 = 0.35 and then multiplying by 80 correctly scales the result: you are taking 35 out of every 100 parts of 80.