EZ Math

Pre-Algebra · Ratios, rates and proportions

How to Find a Unit Price

Problem

12 pens cost $9\text{12 pens cost } \$9

Answer

$0.75 per pen\$0.75\ \text{per pen}

The unit price is the rate with 1 on the bottom. Divide the money by the number of items.

Step-by-step solution

  1. Write the price as a rate.

    $912 pens\frac{\$9}{12\ \text{pens}}

    Why: A rate compares money to items.

  2. Divide the top by the bottom.

    9÷12=0.759 \div 12 = 0.75

    Why: Dividing by 12 gives the price for one pen.

  3. Label the answer with units.

    $0.75 per pen\$0.75\ \text{per pen}

    Why: A unit price always describes one item.

Common mistakes

  • Dividing 12 by 9. The price goes on top.
  • Dropping the units. 0.75 alone does not say per pen.
  • Rounding 0.75 to 0.8. Keep the exact decimal for money.

Practice problems

Use the same method. Work each problem on paper, then open the answer to check.

  1. 5 notebooks cost $10\text{5 notebooks cost } \$10

    Show answer

    $2 per notebook\$2\ \text{per notebook}

  2. 8 markers cost $6\text{8 markers cost } \$6

    Show answer

    $0.75 per marker\$0.75\ \text{per marker}

  3. 3 kg cost $15\text{3 kg cost } \$15

    Show answer

    $5 per kg\$5\ \text{per kg}

  4. 4 bottles cost $6\text{4 bottles cost } \$6

    Show answer

    $1.50 per bottle\$1.50\ \text{per bottle}

  5. 7 bars cost $3.50\text{7 bars cost } \$3.50

    Show answer

    $0.50 per bar\$0.50\ \text{per bar}