Percent Problems

Percent means 'per 100'

To find a percent of a number, change the percent to a decimal and multiply. 25% = 0.25, so 25% of 80 is 0.25 × 80 = 20.

Percent means "out of 100." 25% is 25 per hundred, or 25/100, or 0.25 depending on what form helps you calculate.

To find a percent of a number, convert the percent to a decimal and multiply. To find what percent one number is of another, divide and multiply by 100.

Tax, tip, discount, and markup

1. 1Find the percent amount (the tax, tip, or discount).
2. 2For tax, tip, or markup, add it to the original.
3. 3For a discount, subtract it from the original.

Why this matters

Solve tax, tip, discount, markup, and percent-change problems.

These ideas show up on homework, quizzes, and the next unit in this grade. Getting comfortable here saves time later when the problems stack more steps together.

Common mistakes to avoid

Moving the decimal the wrong direction when converting between percents and decimals.

Treating a percent increase and a percent of a number as the same operation.

Key ideas from this lesson

1. Percent means 'per 100'
2. Tax, tip, discount, and markup
3. Find the percent amount (the tax, tip, or discount).
4. For tax, tip, or markup, add it to the original.
5. For a discount, subtract it from the original.