Discount
A discount is an amount by which the regular price of an item has been reduced. Discounts are typically either in the form of a percentage discount (20% discount) or a flat rate ($5 off). Calculating the latter just involves subtracting the discounted amount from the original price. The final price after discounts, taxes, etc., can be referred to as the sale price.
There are several ways to calculate the sale price given a percentage discount. One method is to determine the amount that the regular price of an item needs to be reduced; this is done by multiplying the discount by the regular price. Then, subtract the discount from the regular price.
Example
What is the sale price if there is a 20% discount on a $30 pair of jeans?
First convert 20% to decimal form: 0.2. Then multiply by the regular price.
0.2 × 30 = $6
With a 20% discount, the jeans will be $6 cheaper, so subtract $6 from the regular price of the jeans:
30 - 6 = 24
The sale price of the pair of jeans is $24.
It is also possible to reduce the number of steps in this calculation by understanding that 20% off of the regular price is equal to 80% of the regular price. Instead of multiplying the regular price by 20% and then subtracting the result from the regular price, we can just find 80% of the regular price.
0.8 × 30 = 24
In either case, the result is the same, and the sale price is $24.
Another type of discount problem is one in which the regular and sale price are known, but the percentage discount is not. To find the percentage discount in this type of problem, divide the sale price by the regular price, then subtract the result from 1.
Example
If the regular price of an item is $37, and there is a $5.55 discount on the item, what percentage discount is there on the item?
First subtract the discount from the regular price to find the sale price:
37 - 5.55 = 31.45
Then, divide the sale price by the regular price, and subtract the result from 1.
31.45 ÷ 37 = 0.85
1 - 0.85 = 0.15
The item was discounted by 15%.