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Maths revision What maths can be used in the question? What strategies will help? What working do I need to show? Is the answer down to maths?

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Presentation on theme: "Maths revision What maths can be used in the question? What strategies will help? What working do I need to show? Is the answer down to maths?"— Presentation transcript:

1 Maths revision What maths can be used in the question? What strategies will help? What working do I need to show? Is the answer down to maths?

2 Number Integers = whole numbers Prime numbers = cannot be ÷ by any number except itself (2, 3, 5, 7, 11, etc) Multiple = in that numbers times table Factor = a number that ÷ into it Square number = the result of a number x itself (1, 4, 9, 16, etc) Square root is the opposite of square

3 Approximations Sometimes an answer is too precise and needs rounding off. e.g. 7.88889934 pence would make more sense to be written as 8p Basically if the number is 5 or larger the previous number rounds up. E.g. 6.547 could be written as 7 or 6.5 or 6.55

4 Decimal places and significant figures These are instructions into how precise the answer must be. Decimal places start from the point. E.g.237.664 = 237.7 to 1 decimal place or = 237.66 to 2 decimal places Significant figures start at the first number E.g. 237.664 = 200 to 1 significant figure or = 240 to 2 significant figures

5 Multiplication 1 2 4 3 6 2 4 8 7 2 3 6 9 4848 1717 7 1 2

6 Decimals 0.2 = 2/10 = 1/5 (20p) 0.02 = 2/100 = 1/50 (2p) If 3 x 4 = 12 Then 0.3 x 4 = 1.2 And 30.0 x 0.4 = 12 And 0.3 x 0.4 = 0.12 etc.

7 Fractions 2 ¼ = 9/4 (4 x 2 + 1 = 9 quarters) 3 4 = 34 ( 3 x 10 + 4 = 34 tenths ) 10 10 12 = 6 = 2 ( cancel by other numbers than 2) 18 9 3

8 Fractions 2 The method for + and – is the same 3 - 2 (think 3 x 4) 4 3 9 8 12 12 X 4 X 3 9 – 8 = 1 12 Include the red arrow

9 Fractions 3 Multiply is easy 2 x 4 = 8 3 5 15 Divide is easy if you turn the 2 nd upside down 2 ÷ 4 becomes 2 x 5 = 10 = 5 3 5 3 4 12 6

10 Fractions 4 To find three quarters (3/4) of a number (32) 132 ÷ 4 = 8 28 x 3 = 24 Three quarters of 32 is 24.

11 Percentages With a calculator 1÷ by 100 2X by the % e.g. find 22% of 600 600 ÷ 100 = 6 6 x 22 = 132

12 Percentages Without a calculator 1Find 10% move the decimal point 1 place 2Find 1% move the decimal point 2 places 3Use these to get to the answer e.g. find 22% of 600 10% = 60.0 and 1% = 6.00 So 22% = 60 + 60 + 6 + 6 = 132

13 Writing as a percentage First write as a fraction Then x by 100 E.g. A car is bought for £10,000 and sold for £8,000. what is the percentage loss? loss = 2,000 x 100 = 2000 = 20% 10,000 100

14 Fractions/Decimals/Percentages To compare change them all to % E.g. Arrange 0.61, 3/5, 59%, 0.599 in order 0.61 = 61 out of 100 = 61% 3/5 of 100 = 60% 0.599 is 59 and a bit out of 100 = 59.9% So 59% then 0.599, then 3/5, then 0.61

15 Negative numbers Go up and down a ladder -3 -3 = -6, -3 +2 -2 = -3 7 -4 -5 = -27 -4 +1 = 4 BUT if there are 2 signs next to each other. -3 - -3 = -3 +3 = 0 7 + -2 + +4 - -5 = 7 -2 +4 +5 = 14 Simplify the signs BEFORE using a ladder

16 Negative numbers Multiplying/dividing/brackets involve the signs coming together -3 x -3 is 3 x 3 and - - = +9 5 x -2 is 5 x 2 and + - = -10 -10 = +212 = -2 -5-6 -3(-5) = +15(-4)² = -4 x -4 = +16

17 Angles Use the rules F z x 180 360 180

18 Ratios Bill and Ben share £30 in the ratio of 3:2 This means that the money is being shared 5 ways The key is to find the value of 1 share £30 ÷ 5 = £6 = 1 share Bill gets £6 x 3 = £18 Ben gets £6 x 2 = £12

19 Area (cm²) (Base x vertical height) halved Remember to halve

20 Area Split into several sections

21 Area Base x vertical height

22 Circles

23 Volume (cm³) Volume = area of A x length l A A A l l l

24 Probability Probabilities are expressed in decimals or fractions. Probabilities lie between 0 (not possible) and 1 (must happen) What is the probability of choosing an 8 in a pack of cards Answer 4 in 52 or 1/13

25 Relative frequency Relative frequency is the number of times that the event is likely to happen e.g. a RF of 0.2 means it will happen one fifth of the time. How many times will the red counter appear in 200 goes if the relative frequency is 0.3 Answer 0.3 x 200 = 60 The relative frequency can be found by experimenting but to be reasonably accurate must be found after numerous goes.

26 Algebra - simplifying Similar terms can be added or subtracted. a + 3a = 4a5y – 2y = 3a BUT 3y – 2a cannot be simplified Simplify 3a – 4y + 2y – 5a + 8y Answer -2a + 6y or 6y – 2a

27 Algebra - simplifying Multiplying 2a x 3b = 6ab 2a x -4a x 3c = -24a²c Dividing 6a ÷ 3a = 210a ÷ 5c = 2a/c 10a²bd = 2ad 5ab Think number/letter/sign

28 Algebra - solving Get rid of brackets Isolate the unknowns on one side Find the value of the unknown 5(a – 2) = 3(a + 6) don’t forget the number 5a – 10 = 3a + 18 5a – 3a = +18 +10 change the signs 2a = 28 find the value of 1 a = 14


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