# Calculating Percentages

To calculate 10% of a quantity, we simply divide by 10.

Many other percentages can be found using mental arithmetic.

 1% Divide by 100 10% Divide by 10 5% Find 10% then half that. 15% Find 10%, find 5% then add them together. 50% Divide by 2. 25% Find 50% then half that. 95% Find 5% then subtract that from the total. 12% Tax in BC (GST + PST). Find 10%. Find 1%, double it. Add to get 12.

Being able to calculate a few of these percentages mentally adds to general numeracy – another building block to confidence when you’re out and about, at home or at work.

15 questions correct wins you a star!

Or, if you happen to be using a calculator, we would perform the following calculations:

 1% Multiply by 1/100 10% Multiply by 10/100 5% Multiply by 5/100 15% Multiply by 15/100 50% Multiply by 50/100 25% Multiply by 25/100 95% Multiply by 95/100 12% Multiply by 12/100

For example, to calculate BC sales tax (12%) on an item that costs \$90:

90 multiply by 12 divide by 100 = 10.80

The sales tax is \$10.80. Therefore the total cost is 90.00 + 10.80 = \$100.80.

As another example, suppose we wish to find 11% of 185.

We type into the calculator: 185 multiply by 11 divide by 100 to get 20.35.