Percent worksheet: discounts, sales tax and tips
Twelve problems in three levels: first the percent of a number, then discounts, sales tax and tips, and finally working backward: the price before tax, the original price before a discount and the percent change. Each problem comes with a percent bar (a tape diagram) that shows what part you pay, what part is taken off and what part is added.
To self-check, each answer has a letter in the answer bank: if everything is right, the letters spell a message. The answers from the most common mistakes (adding the discounts, taking the tax off the total) are in the bank too, with letters that don't fit.
What's included
- 2 student pages: 12 problems in 3 levels, with percent bars and a grid to work on.
- Secret code to self-check.
- 1 teacher page: answer key, the mistake behind each wrong answer and an exit question.
Check your answers
The problems
Solve each problem in the grid. Find your answer in the answer bank (page 2) and write its letter in the box. If all your answers are right, the letters spell a message.
number × X100
price × (1 − X100)
price × (1 + X100)
new − originaloriginal × 100
If a letter doesn't fit, check that problem: the bank includes the answers from the most common mistakes.
For the teacher: answer key and common mistakes
Answer key
- 150 × 0.20 = 30
- 350 × 0.10 = 35
- 360 × 0.05 = 18
- 48 × 0.75 = 36
- 15 × 0.8 = $12
- 280 × 0.85 = $238
- 500 × 1.08 = $540
- 45 × 1.2 = $54
- 216 ÷ 1.08 = $200
- 69 ÷ 0.75 = $92
- (10 − 8) ÷ 8 × 100 = 25%
- 0.8 × 0.9 = 0.72 → you pay 72%: 28% off
The mistake behind each answer in the bank
| Answer | # | Mistake | Answer | # | Mistake |
|---|---|---|---|---|---|
| 7.5 | 1 | 150 ÷ 20 | 508 | 7 | added 8 |
| 3.5 | 2 | moved the decimal point two places | 40 / 9 | 7 / 8 | found only the tax / only the tip |
| 180 | 3 | used 5% = 0.5 | 198.72 | 9 | took 8% off the total |
| 64 | 4 | divided by 0.75 | 86.25 | 10 | multiplied by 1.25 |
| 3 / 42 | 5 / 6 | found only the discount | 20% / 125% | 11 | divided by the new price / didn't subtract 100% |
| 265 | 6 | subtracted 15 | 30% / 72% | 12 | added the discounts / mixed up paid and taken off |
Mistakes to watch for
- Adding successive discounts (20% + 10% is not 30%).
- Removing the tax by taking 8% off a total that already includes it.
- Dividing by the new value when finding the percent change.