Percentage and decimal equivalents
Solve problems requiring knowledge of percentage and decimal equivalents of 1/2, 1/4, 1/5, 2/5, 4/5 and fractions with denominators that are multiples of 10 or 25
What a learner can do afterwards
- State that 1/5 = 20% = 0.2 and use this to find 20% of 60
- Convert 3/4 to 75% and to 0.75
- A shop offers 25% off a £40 item — what is the sale price?
The lesson
You already know that fractions and decimals can show the same amount. Percent is a third way to write it. Percent just means 'out of 100'. A few fractions have percent and decimal partners worth remembering: 1/2 = 50% = 0.5, 1/4 = 25% = 0.25, 1/5 = 20% = 0.2, 2/5 = 40% = 0.4, and 4/5 = 80% = 0.8.
To find 20% of 60, remember 20% is the same as 1/5. So 20% of 60 is 1/5 of 60, which is 60 ÷ 5 = 12.
A shop takes 25% off a £40 jacket. Since 25% = 1/4, the discount is £40 ÷ 4 = £10. The sale price is £40 minus £10, which is £30.
Fractions with a denominator of 10, 20, 25, or 50 turn into percents fast. Scale the fraction so the denominator becomes 100. For 7/20, multiply top and bottom by 5 to get 35/100, which is 35%.
Once you know 1/2, 1/4, 1/5, 2/5, and 4/5 as percents and decimals, you can solve money and amount problems without long division.
Watch it
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.