How to Do Discount Math Problems

Discount math problems are easy if you follow one formula.

Some of the more difficult math problems that a person may come across in school are word problems. Word problems often revolve around everyday uses for the math skills being taught in a given lesson, such as purchasing goods or running a business. One especially common theme for math word problems is discounts, especially when purchasing clothing. In discount math problems you have to first figure out the total for the purchase and the discount that needs to be removed from that number. Then you remove the discount percentage from the total.

Things You'll Need

• Sheet of paper
• Pencil

Instructions

1. Read through the math problem and decide which numbers are the total price and the rate of the discount. The total price or total value of an item or items will be in monetary form while the discount will be a percentage. One example would be two hats that cost $29.98 altogether and a discount of 15% for working at the store that sells the hat.

2. Insert the numbers that represent the price and the discount into the formula P x D (price times discount). Move the decimal of the percentage over two places to the left first, though, to change the percentage into a decimal (use the decimal form for the formula).

3. Multiply the two numbers and you have the discount in monetary form. For two hats that cost $29.98 altogether with a 15% discount, the rounded discount would be $4.50.

4. Subtract the discount number you calculated from the total price of the goods. In the case of two hats at $29.98 with a discount of $4.50, the cost with the discount removed would be $25.48.

5. If sales tax applies, multiply the tax rate (a percentage) by the final value with the discount removed to get the tax for the purchase. In the case of the two hats for $24.48 after the discount, and a tax rate of 7% would be about $1.71. Add the number that represents the tax to the total price after the discount to get the final number that the customer would have to pay (grand total). For the purchase of the two hats, the grand total would be $26.19.

Tips & Warnings

• When estimating numbers that go beyond the hundredth place for monetary values, round to the nearest hundredth. If the number in the thousandths place is four or less, round down. If it is five or more, round up.

References

• Education: Percentages Practice Problems For GED Math