Percentages · Usually met around P6
What a percentage is
A percentage is how many out of 100.
How to do it
Method
A percentage is how many out of 100
37 of 100 squares shaded: 37100 = 37%
Another way
When the whole isn't 100
520 = 25100 = 25%
In full
A percentage says how many out of every 100: 37% (“thirty-seven percent”) means the whole is split into 100 equal parts and we take 37 of them, which is 37100 = 0.37. The whole is 100%. With a picture, first count how many squares there are in all: 37 shaded out of 100 is 37%; the 100 − 37 = 63 unshaded are 63%, and the two parts make 100%. When the whole isn't 100 squares, think of it as 100 parts first: 5 shaded out of 20, each square is 100% ÷ 20 = 5%, so 5 squares are 25%; or scale up: 520 = 25100 = 25%.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
The big square is split into 100 equal squares. The shaded part is □% of the whole.
Show the answer and working
Answer: 8
8 of the 100 squares are shaded: 8100 = 8%.
Example 2
The rectangle is split into 10 equal parts. The shaded part is □% of the whole.
Show the answer and working
Answer: 40
The whole is 100%, so each part is 100% ÷ 10 = 10%; 4 parts are 40%.
Example 3
The big square is split into 100 equal squares, some shaded in two colours. The coloured part is 29% of the whole altogether.
True or false?
Show the answer and working
Answer: False
The two colours have 60 and 11 squares: 71 in all, so 71%.
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