Working out percentages of amounts using a calculator method.

To work out a percentage of an amount (using a calculator) then follow these two simple steps:

Step A. First you need to work out 1% of your number, do this by dividing the amount by 100.

Step B. Multiply your 1% amount by the percentage you require.

Example 1

Calculate 38% of 1500 gallons.

Step A. Fist you need to work out 1% of your number:

1500 ÷ 100 = 15 gallons

Step B. Multiply your 1% amount by the percentage you require:

38% = 15 × 38 = 570 gallons

Example 2

Calculate 53% of 74 kilograms.

Step A. Fist you need to work out 1% of your number:

74 ÷ 100 = 0.74 kilograms

Step B. Multiply your 1% amount by the percentage you require:

53% = 0.74 × 53 = 39.22 kilograms

Example 3

David puts $543 in a savings account for 1 year at an interest rate of 3.5%. Work out how much interest David earns on his money.

Step A. Fist you need to work out 1% of your number:

543 ÷ 100 = $5.43  

Step B. Multiply your 1% amount by the percentage you require:

3.5% = 5.43 × 3.5 = $19.01 rounded to 2 decimal places.

Example 4

In a sale there is 17% off all prices. If a dress costs $61, work out how much discount you get off the price of the dress.

Step A. Fist you need to work out 1% of your number:

61 ÷ 100 = 0.61

Step B. Multiply your 1% amount by the percentage you require:

17% = 0.61 × 17 = $10.37 discount.

Example 5

Last week Martin weighed 63kg. This week he weighs an extra 2%. Work out how much weight Martin has gained.

Step A. Fist you need to work out 1% of your number:

63 ÷ 100 = 0.63

Step B. Multiply your 1% amount by the percentage you require:

17% = 0.63 × 2 = 1.26 kilograms.