Percents at the store and restaurant
Three everyday percent calculations:
| Situation | Effect on price |
|---|---|
| Discount | subtract a percent |
| Sales tax | add a percent |
| Tip | add a percent |
Discounts
A sign says "25% off". The discount is 25% of the regular price.
Example: A $80 jacket is 25% off.
- Discount: 0.25 × 80 = $20
- Sale price: 80 − 20 = $60
- One step: 80 × 0.75 = $60
Sales tax in Canada
Canadian sales tax depends on the province:
| Province | Tax |
|---|---|
| Alberta, territories | 5% GST |
| Ontario | 13% HST |
| Nova Scotia | 14% HST |
| New Brunswick, Newfoundland and Labrador, PEI | 15% HST |
| British Columbia, Manitoba, Saskatchewan, Quebec | 5% GST + provincial sales tax |
Tax rates can change, so check current rates for real purchases.
Example: A $40 game in Ontario.
- Tax: 0.13 × 40 = $5.20
- Total: 40 + 5.20 = $45.20
- One step: 40 × 1.13 = $45.20
Discount, then tax
Take the discount off first, then add tax to the sale price.
Example: $120 shoes, 30% off, 13% tax.
- Sale price: 120 × 0.70 = $84
- With tax: 84 × 1.13 = $94.92
Tips
At restaurants in Canada, people often tip 15–20% of the bill. Many people tip on the amount before tax.
Quick method for 15%: find 10%, add half of it.
Example: A $46 meal.
- 10% = $4.60; 5% = $2.30
- 15% tip = $6.90
For 20%: find 10% and double it: $9.20.
Total with tax and tip
Example: $46 meal, 13% tax, 15% tip on the pre-tax amount.
- Tax: $5.98
- Tip: $6.90
- Total: 46 + 5.98 + 6.90 = $58.88
Worked examples
Example 1: A $15 T-shirt is 40% off. Sale price?
15 × 0.6 = $9.
Example 2: A $250 phone with 5% GST. Total?
250 × 1.05 = $262.50.
Example 3: A tip of 18% on $35?
0.18 × 35 = $6.30.
Common mistakes
- Subtracting the percent number as dollars: 25% off $80 is not $55.
- Adding tax before the discount (the result is the same mathematically, but stores calculate tax on the sale price; it’s clearer to discount first).
- Forgetting to add tax when budgeting.
Try it yourself
- A $60 sweater is 15% off. Sale price?
- A $24 book with 13% HST. Total?
- 20% tip on a $55 bill?
- $200 boots, 35% off, then 13% tax. Total?
Answers: 1) $51 2) $27.12 3) $11 4) $146.90
Quick recap
- Discount: × (1 − rate). Tax and tip: × (1 + rate) or add on.
- Apply discounts before tax.
- 10% is a quick starting point for mental tips.