One of the easiest ways to determine a 10 percent discount is to divide the total sale price by 10 and then subtract that from the price. You can calculate this discount in your head. For a 20 percent discount, divide by ten and multiply the result by two. Or you can use one of two other methods for calculating the 10 percent discount without needing a calculator.
Figuring the Discount
While 10 percent of any amount is the amount multiplied by 0.1, an easier way to calculate 10 percent is to divide the amount by 10. So, 10 percent of $18.40, divided by 10, equates to $1.84. To figure the total cost with the 10 percent discount, take $18.40 and subtract $1.84 which equates to a total sales price of $16.56.
Notice that 10 percent of $18.40 can also be found without doing any math at all. Simply move the decimal point one digit to the left to yield the 10 percent discount. This is applicable to any value. Ten percent of $1,369.98 is $136.998, or roughly $137, for a discounted price of $1,369.98 minus $137, or $1,232.98.