Foundation and Higher · percentage change

Percentage increase
and decrease.
One multiplier.

start from 100%

the original amount is always —

100%

increase by 15%: you now have 115%

decrease by 15%: you now have 85%

step 1 of 4

Increase

1. Add the percentage to 100%.

2. Divide by 100 for the multiplier: 1.15.

✓ One calculation: 80 × 1.15

increase £80 by 15%

100% + 15% = 115% = 1.15

80 × 1.15 = £92

step 2 of 4

Decrease

1. Subtract the percentage from 100%.

2. The multiplier is 0.85, not 0.15.

✓ 0.15 gives the discount, not the price

decrease £80 by 15%

100% − 15% = 85% = 0.85

80 × 0.85 = £68

step 3 of 4

Find the % change

1. Find the change.

2. Divide by the original, not the new.

✓ Change ÷ original × 100

£40 rises to £52

change = 52 − 40 = 12

1240 × 100 ÷ original

= 30% increase

step 4 of 4

Profit and loss

1. Same formula. The original is the cost.

2. 50 ÷ 250 = 0.2.

✓ Say whether it is a profit or a loss

bought for £250, sold for £200

loss = 50

50250 × 100 = 20% loss

percentage change —

Increase

multiplier above 1: 1.15

Decrease

multiplier below 1: 0.85

Find the change

change ÷ original × 100

A 5% increase is × 1.05,
not × 1.5.

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