Percentages

Per cent means "per hundred". A percentage is just a fraction out of 100. For example, 50% = 50/100 = one half. So 50% of a class of 30 students is 15 students.

To find a percentage of an amount, turn the percentage into a decimal and multiply. For example, to find 20% of 150: 20% = 20/100 = 0.2, and 0.2 × 150 = 30.

For a decrease, work out the percentage and take it away. A sale of 25% off a $80 pair of shoes: 25% of $80 = $20, so the sale price is $80 − $20 = $60.

An increase works the same way, but you add it on. A $40 ticket that goes up by 15%: 15% of $40 = $6, so the new price is $40 + $6 = $46.