Lesson 1 of 1524
Fractions, decimals, and percents
The same amount can be written three ways.
Practice this chapterA fraction a/b means a divided by b. One half is 1 ÷ 2, which is the decimal 0.5.
A percent is a fraction out of 100. So 50% is 50/100, which is 0.5, and 8% is 0.08. To turn a percent into a decimal, move the decimal point two places left.
The word “of” after a percent means multiply. Eight percent of 250 is 0.08 × 250.
Percent of a number
part = (percent ÷ 100) × whole
Turn the percent into a decimal, then multiply.
Worked example
What is 3/4 of 60?
- 1“Of” means multiply, so the question is 3/4 × 60.
- 23/4 means 3 ÷ 4. That division is 0.75, so the product is also 0.75 × 60.
- 30.75 × 60 = 45.
- 4The same work with the fraction: (3 × 60) / 4 = 180 / 4. Then 180 ÷ 4 = 45.
- 5One quarter of 60 is 60 ÷ 4 = 15. Three of those quarters are 3 × 15 = 45.
Result: 45
Why. Three quarters of 60 is 45 because each quarter is 15, and three of them make 45. The decimal 0.75 is the same fraction, so it gives the same product.
8% is 0.08, not 0.8. One missed decimal place makes the answer ten times too big.
Practice margin
This chapter
A fresh set from this chapter only. Choose 10 or 20. Multiple choice and fill-in, with no repeat inside the set.