How to calculate sales tax in your head

If you ever have a basket full of grocery items and want to get a rough idea of ​​the sales tax you’ll pay, here’s a guide on how to quickly and accurately calculate your tax bill.

This depends on the state you’re in: some states have rates as low as 0% (no sales tax), up to almost 10%. You can determine your state’s rate by reviewing a receipt from a recent purchase. The total sales tax will be displayed and is typically between 5-9%.

(1) Round your purchase to the nearest ten. If your total purchase is $476.99, round up to $480.

(2) Know your state tax rate and round to the nearest whole number. This can be as low as 5% or as high as 9%.

(3) Follow these tricks to calculate your tax and total:

5%:

(a) Divide the total of your purchase by 10, that is: delete the last zero of the total. So $480 becomes $48.

(b) Now divide by 2. So $48 becomes $24, your approximate sales tax.

6%:

Follow the steps for the 5% tax. Now divide your original amount by 100 (change the decimal place to two), so that $480 becomes $4.80, or about $5.

Now add this amount to the 5% sales tax: $24+$5=$29.

7%:

Same as 6%, but add the total divided by 100 twice. So $24+$5+$5=$34.

9%: Divide your total by 10, so $48. Now divide this by 10 again and subtract: $4.8, or about $5, so $48-$5 = $43.

8%: Follow the same steps as for the 9% sales tax, but subtract twice: $48-$5-$5=$38.

By following these steps, you can quickly calculate the tax on any item you are purchasing.

Here’s another common mental math question: How can you quickly estimate, in your head, a fair tip for your waiter or waitress?

Most advice says we should tip 15-20%. Here’s how to quickly estimate the top you give to a server.

Let’s say your restaurant bill is $53.

(1) Divide this by 10: $5.30

(2) Multiply this by 2: $10.60, or about $11.00.

(3) The midpoint between these 2 is the 15% tip, in this case around $8.00.

(4) The amount in (2) is a more generous 20% tip.

Choose an amount between (2) and (3) if your service was very good.