Percentages are a crucial skill you'll use a lot in real life - like wage increases, inflation rates, and interest rates. No wonder they're a big part of KS3 Maths. This quiz focuses on calculating increases and decreases in terms of percentages.
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Finding a new value when something goes up or down by a percentage can be done in various ways. One easy method is to multiply by a decimal number. For example, if a £200 item has a 5% decrease, multiply £200 by 0.95 (95% of the previous price). For a 5% increase, multiply by 1.05 (105% of the previous price). There are other methods, so feel free to explore!
Practice with this quiz on percentage increases and decreases - use any method you like! Good luck with your KS3 Maths journey!
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You can find more about this topic by visiting BBC Bitesize - Percentages
One way is 20 / 100 x £299 = £59.80. Then subtract £59.80 from £299 to get £239.20
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Another way is to use a multiplier. A 15% decrease is a mutliplier of 100 - 15 = 85%. 85% = 0.85 (just divide 85 by 100). £690 x 0.85 = £586.50
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A 12% increase is a multiplier of 1.12. 1.12 x 140 = 156.8
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If something is increased by x% then its original value will have to be multiplied by (1 + x) to find the new value. The 1 represents 100% and the x represents the percentage increase: in this case (1 + x) = (1 + 0.13) = 1.13. If there was a decrease of x%, then you would have to multiply the original value by (1 - x)
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Percentages are easily converted to decimals. Just divide by 100 (or move digits)
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4.4% of 22,500 is 990. To work this out you could multiply 22,500 x 0.044 (4.4 hundredths)
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To work out 20% just divide by 5
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Calculations are much easier if a multiplier is used
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To find 14% multiply by 0.14
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To find 17% multiply by 0.17
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