When you are using decimals, percentages, fractions and ratios the main purpose is to get a new value. To get this new number we need to multiply. ×

Decimals are the easiest to use. Just multiply the decimal by the total. e.g. Find 0.55 of × 300 = 165 Find 0.04 of × 50 = 2

Fractions are almost as easy as decimals. You have two choices. 1.Use the fraction button on the calculator. 2.Change the fraction into a decimal by dividing the top by the bottom. Then solve the problem just like it was a decimal.

e.g. Find ½ of 85. ½ × 85 = 42.5 or 1 ÷ 2 = × 85 = 42.5

First change them into a decimal by dividing by 100. Then solve by multiplying. e.g. What is 15% of 60? 15 ÷ 100 = × 60 = 9

First change the ratio into two fractions. The top number is one of the numbers in the ratio. The bottom number is the total. e.g.4 : 5 4/9 and 5/9 are the two fractions 3 : 18 3/21 and 18/21 are the two fractions

When you have the fractions you can solve the question by multiplying. You will two answers, one for each fraction. e.g. $600 is split between Frank and Emma in a ratio of 2 : 3. Fractions are 2/5 and 3/5 Frank 2/5 × 600 = $240 Emma3/5 × 600 = $360

When a question says to increase an amount by a decimal, fraction or percentage you do it in two steps. 1.Work out the percentage of. 2.Add the answer to the starting total.

e.g.Your savings of $200 increase by 30%. How much do you have? 30 ÷ 100 = × 0.3 = $ = $260 A 6 metre tree grows by ¼. What is its new height? 6 × ¼ = 1.5m = 7.5m

When a question says to decrease an amount by a decimal, fraction or percentage you do it in two steps. 1.Work out the percentage of. 2.Subtract the answer from the starting total. `

e.g. The level of water in the pool decreases by ¾. The level starts at 1.2m 1.2 × ¾ = 0.9m 1.2 – 0.9 = 0.3m The shoes have a price-tag that reads $120. The store is having a 20% off sale. How much will the shoes cost? 20 ÷ 100 = × 0.2 = $ – 24 = $96

When you want a number from the past you have to work backwards. You must divide. Usually this is done to find out what a number used to be before that number was increased or decreased. e.g.GST is 15%. A car costs $ after GST is added. How much does it cost without the GST?

Add 1 to the increase and divide the total by this number. e.g. GST is 15%. A car costs $ after GST is added. How much does it cost without the GST? 15 ÷ 100 = = ÷ 1.15 = $20 000

Take the decrease away from 1. Divide the total by this number. A leather jacket costs $150 during a 25% off sale. How much did it cost before the sale? 25 ÷ 100 = – 0.25 = ÷ 0.75 = $200