Percentages

A percentage is a fraction of 100.

 

(30 in each 100) as a fraction is .

as a decimal is 0.3.

Often, you need to find a percentage of a quantity. First, write the percentage as a fraction or a decimal, then multiply by the quantity.

 

 

Percentage increase and decrease

In some questions you are given the cost price and the selling prices and have to find the percentage increase or decrease. This means you need to find one amount as a percentage of another. You form a fraction from the two amounts and multiply this by 100. Try these questions.

Simple interest

With simple interest the amount of money borrowed remains fixed.

For example is borrowed for 3 years at an interest rate of pa (pa means per annum, or each year).

Interest for one year = of

=

Interest for 3 years = .