BuilderGrades 6–7⏱ 15 min

Percentages

Shade a hundred grid, line up percents with amounts, and work out real discounts.

Standards: 6.RP.A.3c7.RP.A.3

1Wonder

A $60 pair of shoes is “25% off”. Your phone battery says 40%. Your test score is 18 out of 20, which is 90%. What does “percent” actually mean, and how do you work these out?

2Explore

Percent lab

This activity needs a bigger screen

Turn your phone sideways, or open this lesson on a tablet or computer. The explanation and quiz below work here.

Percent 30 % The whole 80 Shopping: take it off the price

Try this

Drag on the grid to shade 50%. What fraction is that? Where is the purple line on the bar?
Set the whole to 80 and the percent to 10%. Now try 20% and 30%. What pattern do you see?
Find a percent where the part is exactly half of the whole, whatever the whole is.
Turn on Shopping. A $60 item is 25% off. How much do you pay?

3Explain

Step 1 of 5

Per cent means “per hundred”

The grid has 100 squares. 37 of them are shaded, so 37 out of 100, or 37%, is shaded. Each square is 1%.

Percent

p\% = \frac{p}{100} \qquad p\% \text{ of } n = \frac{p}{100} \times n

A percent compares a part with a whole of 100. To find a percent of a number, turn the percent into a fraction or decimal and multiply.

4Practice

Question 1 of 5

What is 50% of 30?

5Recap

Percent means “out of 100”: 37% = 37/100.
Percents, fractions and decimals are three ways to write the same thing: 25% = 1/4 = 0.25.
p% of n = p/100 × n.
10% is the number ÷ 10; build other percents from it.
A discount of p% means you pay (100 − p)% of the price.