Finding a percentage of an amount…..

Finding a percentage of an amount….. without a calculator!

No more of these …..

or these…..

100% is…… the whole amount

Start by finding 10% Easy enough to do because 10 x 10% = 100%

So to find 10%... just divide by 10

Find 10% of 48 10% of 48 = 48 ÷ 10 = 4.8

Find 10% of 590 10% of 590 = 590 ÷ 10 = 59

Your turn • 10% of 58 = 58÷10 = 5.8 • 10% of 50 = 50÷10 = 5 • 10% of 140 = 140÷10 = 14 • 10% of 5.4 = 5.4÷10 = 0.54 • 10% of 21.4 = 21.4÷10 = 2.14

You must set our your answers correctly Like mine that means

In a sale a pair of trainers which cost £48 originally are reduced by 10%. Find the ‘sale price’. 10% of £48 = 48÷10 = £4.80 Sale price = £48 - £4.80 = £43.20 Exam question

One for you I get a 10% discount if I use my Hull City credit card in the shop. How much would I pay if I used my card to buy a shirt priced at £38.60?

and the answer….. 10% of £38.60 = £38.60 ÷ 10 = £3.86 ‘card price’ = £38.60 - £3.86 = £34.74

Finding 20% • First find 10% (by dividing by 10) • Then ‘double it’ (2 x 10% = 20%) • Do NOT just divide by 20 – it will not work

Example - Find 20% of £56 10% of £56 = £56 ÷ 10 = £5.60 20% of £56 = 2 x £5.60 = £11.20

If you can find 10% then…. • 20% = 2 x 10% • 30% = 3 x10% • 40% = 4 x 10% • 70% = 7 x 10% and so on…

Find 30% of 85 kg 10% of 85 kg = 85 ÷ 10 = 8.5 kg 30% of 85 kg = 3 x 8.5 = 25.5 kg

5% = 10% ÷ 2

2.5% = 5% ÷ 2

Find 35% of 82 10 % of 82 = 82 ÷ 10 = 8.2 30% of 82 = 3 x 8.2 = 24.6 5% of 82 = 8.2 ÷ 2 = 4.1 35% of 82 = 24.6 + 4.1 = 28.7 (30% + 5% = 35%)

V.A.T. is charged at 17.5% on new cars. If a car is purchased for £12000, calculate the V.A.T. 10% of £12000 = £1200 5% of £12000 = £600 2.5% of £12000 = £300 17.5% of £12000 = 1200+600 + 300 = £2100 Exam question

Finding a percentage of an amount…..