Percentage guide: from meaning to method
Understand percentages, percentage amounts and changes without relying on guesswork.
A little clearer.
Per cent means per hundred
A percentage describes a quantity relative to one hundred. You can write the same proportion as a percentage, a fraction or a decimal.
Find a percentage of an amount
Convert the percentage to a decimal and multiply by the original amount. For some percentages, mental methods are also helpful: finding ten per cent and five per cent separately can make fifteen per cent easier to calculate.
Compare a change with the original value
Percentage change measures the difference relative to the starting value. The original value is the denominator, which is why reversing a percentage increase requires care.
For an increase from eighty to one hundred, the change is twenty. Compared with the original eighty, that is twenty-five per cent.
Keep the context in view
A percentage alone does not tell you the size of the original amount. The same percentage of two different amounts can give different results.
Use the percentage calculator to check a calculation, then look back at the method. A calculator can confirm arithmetic, but understanding what the percentage refers to is still essential.
