# Finding the sale price without a calculator given the original price and percent discount

In this lesson, we learn how to find a sale price, given the original price and a percent discount without a calculator.

Rules for finding the sale price given the original price and percent discount

• At first, we consider the original price and discount rate.

• The rate is usually given as a percent.

• To find the discount, multiply the rate by the original price.

• To find the sale price, subtract the discount from original price

• For finding the sale price without a calculator we use mental math methods as shown in the solved examples below.

A shirt is put on sale for 40% off the regular price. If the regular price is $90 what is the sale price? ### Solution Step 1: Regular price =$90

Discount percent = 40% off $90; Step 2: 10% of 90 can be found by shifting the decimal point one place to left as$9.0. 40% of $90 is 4 times this amount, i.e., 4 ×$9.0 = $36.0 So, discount =$36.0

Step 3:

Sale price = Original price – Discount = $90 –$36 = $54 A dress is put on sale for 20% off the regular price. If the regular price is$110 what is the sale price?

### Solution

Step 1:

Discount percent = 20% off $110; Step 2: At first, we find the 10% of$110.0. Here we shift the decimal one place to left and get $11.0. To find 20% we double this amount as 2 ×$11 = $22 So, Discount =$22

Step 3:

Sale price = Original price – Discount = $110 −$22 = \$88