How to calculate sales tax

Calculating Sales Tax: A Guide for 7th and 8th Graders

What is sales tax?

A social studies mini lesson here: Sales tax is a small percentage of the cost of a good or service that you have to pay when you buy it. This money goes to your local, county, or state government to help pay for public services like schools, roads, and parks. Now, whether or not this tax money is being spent wisely and efficiently is another matter. If you don't think it is, you should become an informed voter and leader in your community. 

How to calculate sales tax

To calculate the sales tax on an item or service, you need to know two things:

• The price of the item
• The sales tax rate (This is usually given as a percentage)

Steps to calculate sales tax:

• Convert the sales tax rate from a percentage to a decimal.
• Multiply the price of the item by the decimal sales tax rate.
• Add the sales tax amount to the original price to get the total cost.

Here are several step-by-step examples:



Example 1: Buying a T-Shirt

Price of T-Shirt: $20
Sales Tax Rate: 5%

Convert 5% to a decimal: 0.05.
Calculate the sales tax: $20 × 0.05 = $1.
Add the sales tax to the original price: $20 + $1 = $21.

Total Cost: $21

Example 2: Buying a Book

Price of Book: $15
Sales Tax Rate: 7%

Convert 7% to a decimal: 0.07.
Calculate the sales tax: $15 × 0.07 = $1.05.
Add the sales tax to the original price: $15 + $1.05 = $16.05.

Total Cost: $16.05

Example 3: Buying a Pair of Shoes

Price of Shoes: $45
Sales Tax Rate: 6.5%

Convert 6.5% to a decimal: 0.065.
Calculate the sales tax: $45 × 0.065 = $2.925 (which we can round to $2.93 for simplicity).
Add the sales tax to the original price: $45 + $2.93 = $47.93.

Total Cost: $47.93

Practice problems:



Now it's your turn! Try to calculate the total cost for the following items:

• A skateboard that costs $60 with a 7% sales tax.
• A book that costs $25 with a 4% sales tax.
• A backpack that costs $30 with a 6% sales tax.

Tips and tricks

• Always convert the percentage to a decimal first. Move the decimal point two places to the left or divide by 100.
• Double-check your math. It's easy to make small mistakes, so take your time.
• Practice! The more you practice, the easier it will become.

By following these steps, you'll be able to quickly and easily calculate sales tax on any good or service you buy. Happy shopping and calculating!