How_To_Be_Good_At_Math

NUMBERS • PERCENTAGE CHANGES 69

5% of £200 = £10 30% of £250 = £75

Turning a percentage increase

into an amount

Turning a percentage decrease

into an amount

Now take a look at this bike. It used to cost

£250, but its price has been cut by 30%. If we

buy the bike now, how much money will we save?

One year ago, this bike cost £200. Since then,

its price has gone up by 5%. How much more

does it cost now?

200 ÷ 100 = 2 250 ÷ 100 = 2.5

2 × 5 = 10 2.5 × 30 = 75

These trainers

were £50 but have

been reduced by 30%.

Answers on page 319

Percentage values

In a sale, these items have

been reduced in price. Can you

work out the new prices? To work

out the new price, calculate the

decrease in price and subtract

it from the original price.

A coat priced

£200 has been

reduced by 50%.

This T-shirt has

been reduced

by 10%. It was £15.

30%

off

The original

price

1% of the

original price

1% of

250

TRY IT OUT

5% of £200 =? 30% of £250 =?

Just as in our example with the other bike, the

first step is to work out 1% of the original price.

This is 250 ÷ 100. The answer is 2.5.

First, we need to find 1% of 200. All we need to

do is divide 200 by 100. Remember, we looked

at dividing by 100 on page 136. The answer is 2.

Now we know what 1% is, we can find 30%

like this: 2.5 × 30 = 75

We want to find 5%, so we multiply the value

of 1% by 5. This is 2 × 5, and the answer is 10.

This means the bike now costs £10 more

than it did a year ago.

This means the price of the bike has

dropped by £75.

068-069_Percentage_increase.indd 69 29/02/2016 14:10