Canadian Money Math: Dollars, Cents, Change, and Percent

Read dollars and cents as hundredths

In $12.45, the 12 is the number of dollars and the 45 is the number of cents. Since one dollar is 100 cents, 45 cents is 0.45 of a dollar. The decimal point separates the whole dollars from the part of a dollar.

When adding prices, line up the decimal points: $12.45 + $3.80 = $16.25. Writing $3.80 instead of $3.8 makes the cents place visible and reduces place-value mistakes.

Estimate before making change

If a notebook costs $7.65 and you pay with $20.00, the change is $12.35. A quick estimate of $20 − $8 ≈ $12 tells you the exact answer is in a sensible range.

1. Round the price and the amount paid to friendly numbers.
2. Subtract the price from the amount paid using the exact decimals.
3. Check that the change is positive and smaller than the amount paid.

Use percent as a hundred-part relationship

A percentage describes a part out of 100. To find 15% of $40, calculate 0.15 × 40 = 6, so the amount is $6.00. You can also split 15% into 10% and 5%: $4 + $2 = $6.

Taxes and fees are not one universal number across Canada; they can depend on the province, territory, product, and situation. The math skill is the same: convert the stated rate to a decimal, multiply by the eligible amount, and add the result only when the question asks for a total.

Keep a sensible precision

For everyday prices, keep two decimal places for cents. If an intermediate calculation produces more places, keep extra digits until the final step and then round according to the instructions. Estimation remains valuable even when a calculator gives the exact decimal.