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