A percentage is a proportion that shows a number as parts per hundred. The symbol '%' means 'per cent'. 9% means 9 out of every 100, or .
Percentages are just one way of expressing numbers that are part of a whole. These numbers can also be written as fractions or decimals. 50% can also be written as a fraction, , or a decimal, 0.5. They are all exactly the same amount.
Knowledge of converting between decimals, fractions and percentages is required.
Percentages of amounts can be calculated by writing the percentage as a fraction or decimal and then multiplying it by the amount in question.
Find 16% of 40.
16% is the same as .
To find 16% of 40, multiply by 40:
(to divide by 100, bring the decimal place in by two places)
This example could also be worked out by converting the percentage to a decimal. However, this method may be easier to do if a calculator is available.
16% is the same as 0.16. To find 16% of 40, multiply 0.16 by 40:
Percentages of amounts can also be found using known facts about percentages. The most helpful of these facts is how to find 10% of an amount.
This means that 10% is equivalent to dividing by 10, or finding of the amount.
As finding 10% of a number means to divide by 10, it is common to think that to find 20% of a number you should divide by 20 etc. Remember, to find 10% of a number means dividing by 10 because 10 goes into 100 ten times. Therefore, to find 20% of a number, divide by 5 because 20 goes into 100 five times.
Once 10% of an amount is known, this can be manipulated to find other amounts such as 5% or 1%, or any amount that is helpful to answer the question.
Find 27% of 80.
Start by finding 10% of 80 by dividing 80 by 10:
The question asks for 27%, so double 10% to get the 20% needed:
Now that 20% has been found, the remaining amount to calculate the full 27% is 7%. This can be done in lots of different ways, but one of the easiest ways is to find 1% and multiply this by 7.
1% = so 1% can be found easily by dividing the amount by 100.
1% of 80 =
So 7% = .
20% of 80 = 16 and 7% of 80 = 5.6
27% of 80 =