A bicycle costs $120. You must pay an 8% sales tax rate. Explain how to use mental math to find the amount of tax on the bicycle?

I really had to do mental math this would be my thought process

$100, eight percent of if would be 8 dollars

Then I'll figure out how much is ten percent of $10 which is $0.8 and add 0.8 + 0.8 together to get 8 percent of $20

Then I'll add it all together

8 + 1.6 = 9.6

120 + 9.6 = $129.6

If you can do this mentally then do this equation below

120 x 1.08 = $129.6