How it works
p% of a number is (p ÷ 100) × the number. So 20% of 170 = 0.2 × 170 = 34. To ask "what percent of A is B", compute B ÷ A × 100.
Use multipliers. A 25% increase multiplies by 1.25, and a 20% discount multiplies by 0.80. For successive changes, multiply the multipliers. The percents do not simply add: up 20% then down 20% gives 1.2 × 0.8 = 0.96, a 4% loss overall.
To undo a change, divide by the multiplier. If a price after a 20% discount is $56, the original was 56 ÷ 0.8 = $70.
Percents practice problems with solutions
These problems come from Mathyessy's question bank. Try each one before opening the solution.
What is 20% of 170?
Show answer and solution
Answer: 34
20% = 0.2, and 0.2 × 170 = 34.
A $112 shirt is 24% off. What is the discount in dollars?
Show answer and solution
Answer: $26.88
24% of 112 = 0.24 × 112 = 26.88. (The sale price would be 112 − 26.88 = 85.12.)
What percent of 167 is 48.43?
Show answer and solution
Answer: 29%
48.43 ÷ 167 = 0.29, which is 29%.
A price is raised 25% then discounted 20%. What percent of the original price remains?
Show answer and solution
Answer: 100%
Multiply the multipliers: 1.25 × 0.80 = 1.00. The price ends exactly where it started: 100%.
Keep going
Related topics
Related practice sets in the app
All Algebra topics · Contest math practice by topic · MATHCOUNTS practice · AMC 8 practice