Finding a percentage of a total amount without a calculator: Sales tax, commission, discount

In this lesson, we solve problems on finding a percentage of a total amount without a calculator involving sales tax, commission and discount.

Consider the following solved examples.

The sales tax on a $1050 computer system is $63. What is the sales tax rate?

Solution

Step 1:

Price of the computer = $1050

Sales tax = $63

Step 2:

Rate of Sales tax = $\lgroup\frac{\$63}{\$1050}\rgroup \times 100$

= 6%

At a store, a $60 dress is sold at a discount of $12? What is the percentage of discount and sale price of the dress?

Solution

Step 1:

Discount = $12

Marked price of dress = $60

Step 2:

Percentage of discount = $\lgroup\frac{\$12}{\$60}\rgroup \times 100 = 20\%$

Sales price of the dress = $60 − $12

= $48

Mike is a salesman who earns a base salary of $360 per week plus $567 as commission on sales. What was Mike’s percentage of commission and weekly salary if his total sales for the week were $6300?

Solution

Step 1:

Total sales for the week = $6300

Commission on sales = $567

Step 2:

Percentage of commission = $\lgroup\frac{\$567}{\$6300}\rgroup \times 100 = 9\%$

Base salary = $360

= $360 + $567 = $927