Question

Estimate the tax on tires that cost $498 with a 6.25% sales tax

Answer 1

498 x .0625 = 31.125

498 is the cost of the tire
6.25% as a decimal is .0625
31.125 is the actual tax of the item.

If you want to estimate (like with no calculator) then you would simply take 498, round it up to 500 then lower the tax to 6% Which is .06 as a decimal.

Multiply 500 by .06, and you get 30 (Don't forget to move the decimal or you will get a larger number)