# Year 8 Maths **

Maths for year 8 **

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• Created by: Lizzie
• Created on: 22-05-12 19:53

## Negative Numbers

• if a sum has two minuses next to each other, it turns into a plus eg. 7--7=14 (7+7=14)
• if a sum has a plus and a minus next to eachother, it turns into a minus eg. 7+-7=0 (7-7=0)
• if you are multilpying a negative number by a positive number, the answer will be negative eg. -7x7=-49
• if you are multiplying two negative numbers, the answer will be positive eg. -7x-7=49
• this is the same with division eg. -6/2=-3    -6/-2=3
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## Fractions, Decimals and Percentages

• 1/10, 0.1 and 10% are all equal
• 1/5 is 20% or 0.2
• to find a fraction as a percentage, times the bottom by somthing to get 100, and whatever 'something' is, times the top by it aswell eg. 3/5       5x20=100  3x20=60  3/5=60/100=60%
• to convert a percentage to a fraction take the number and put it over 100 eg. 50%=50/100    after that see if you can cancel it down any further eg. 50/100=1/2
• to convert a decimal into a fraction take the significant numbers (ie not 0) and if it is 1 digit put it over ten, but if it is 2 digit put it over 100. then, cancel it down if you can eg. 0.5=5/10=1/2 or 0.25=25/100=1/4
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## Percentage of an Amount

• to find the pergentage of an amount, try to find significant percentages like 1% and 10% and then times the answer by whatever number you need eg. 40% of 50   10% of 50=5    5x4=20  40% of 50=20
• percentages work when they are reversed eg. 40% of 50=20  50% of 40=20!
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