Cambridge O Level Mathematics (Syllabus D) · Syllabus 4024 · Number
Percentages
What is Percentages?
A percentage is a number of hundredths, so a percentage of a quantity is that quantity multiplied by the percentage over one hundred. Any percentage increase or decrease can be carried out in a single step by multiplying by one plus or minus the percentage as a decimal, and reversing such a change means dividing by that same multiplier rather than applying the opposite percentage.
This definition is part of the Number chapter in Cambridge O Level Mathematics (Syllabus D).
Percentages in context
Fractions, decimals and percentages are one number wearing three coats. Choose the coat that suits the job: fractions for exact work and cancelling, decimals for ordering and calculator entry, percentages for comparison and change. The conversions themselves are only three operations — divide, use place value, and multiply or divide by 100 — and every one of them is reversible.