Stores buy items from a wholesaler or distributer and increase the price when they sell the items to consumers. The increase in price provides money for the operation of the store and the salaries of people who work in the store.

A store may have a rule that the price of a certain type of item needs to be increased by a certain percentage to determine how much to sell it for. This percentage is called the markup.

If the cost is known and the percentage markup is known, the sale price is the original cost plus the amount of markup. For example, if the original cost is $4.00 and the markup is 25%, the sales price should be $4.00 + $4.00*25/100 = $5.00.

A faster way to calculate the sale price is to make the original cost equal to 100%. The markup is 25% so the sales price is 125% of the original cost. In the example, $4.00 * 125/100 = $5.00.