Maths unit 2 revision guide !

covers everything in topic 2 maths edexcel

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Negative numbers
When +/-
This is basically the reverse of what it is :
Adding a negative subtracting it
Subtracting a negative adding it
When Multiplying
Positive × positive = positive
Negative × negative = positive
Positive × negative = negative
Negative × positive = negative
If the signs are the same, the answer is positive. If the signs are different, the answer is negative.
X'S AND /
To calculate 158 × 67:
1. First, multiply by 7 (units):
158
x 67
____
1106
2. Then add a zero on the right-hand side of the next row. This is because we want
to multiply by 60 (6 tens), which is the same as multiplying by 10 and by 6.
Now multiply by 6:
158

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Now add your two rows together, and write your answer.
10586
To calculate 748 divided by 51,
1. First, set the sum out as shown:
2. We work out 74 divided by 51, and write the answer above the 4.
1 × 51 = 51, so we write this underneath 74.
Subtract 51 from 74 to get the remainder (23).
3. We now bring down the next digit (8) and write it on the end of the 23.
4.…read more

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Primes:
Prime numbers only divide by themselves and 1, but 1 is NOT a prime number!!
APART FROM 2 AND 5 ALL PRIMES END IN 1,3,7 OR 9 !!
BUT NOT ALL NUMBERS ENDING IN THESE ARE PRIME NUMBERS!!
Factors
The factors of a number are any numbers that divide into it exactly. This includes 1 and the number
itself.
For example, the factors of 6 are 1, 2, 3 and 6. The factors of 8 are 1, 2, 4 and 8.…read more

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What is the biggest number that goes into both numbers?
Method 1:
1.Here are the list of prime factors of 24 and 36:
24 = 2 x 2 x 2 x 3
36 = 2 x 2 x 3 x 3
2.…read more

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Method 2:
1.Work out the HCF factor of each number.
24 = 1,2,3,4,6,8,12,24
36=1,2,3,4,6,9,12,18
2.X's the 2 numbers together then divide by the highest factor
(24 x 36) / 12 = 72
So 72 is the LCM of 24 and 36
Method 3:
1. Work out the primes of each number
2. Find the highest prime of each number
3.…read more

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X by 100 eg 0.5 x 100 = 50 %
Percentage decimal
/ by 100
Decimals fractions
If there is one number it goes over 10, 2 numbers go over 100
0.6 = 6/10 , 0.12 = 12/100
If the decimal repeats with a single digit, the denominator will be 9:
0.2222222... = 2/9
0.6666666... = 6/9 = 2/3
If the decimal repeats with two digits, the denominator will be 99:
0.24242424...…read more

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Recurring decimals with whole numbers
If a recurring decimal has a number in front of it, then it simply means it is a whole number + the
remaining decimal
Eg 1.33333
This means the fraction would be 1
Fractions
Fractions of a quantity
How do we find 3/5 of 20?
to find 1/5 of 20, then multiply by 3.
1
/5 of 20 is 20 ÷ 5 = 4.…read more

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Dividing
The rule when dividing two fractions is to turn the second fraction upside down, and
multiply.
Eg 2/3 ÷ 3/4 we work out 2
/3 × 4/3 = 8/9
Remember we only turn the fraction we are dividing by (the second one) upside down.
Mixed fractions
This is when there is a whole number, numerator and denominator.
Percentages
Increasing percentages:
A radio is increased at £30 by 15%
= 15 x 0.3 = 4.50
4.50 + 30 = £34.…read more

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Working out the original price of something after a decrease.
Eg a car falls in value by 30% in a year.…read more

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Whenever a measurement is rounded off to a given unit the actual measurement can be anything up
to half a unit bigger of small eg:
A room is given as being 9m long to the nearest metre ­ its actual length could be anything from
8.5m to 9.5m ie half a metre either side of 9m
If it was given as 9.4m to the nearest 0.2m it could be anything from 9.3m to 9.5m ie 0.…read more

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