Explain how you could use mental math to find a 15% tip for a $26 restaurant bill.

10% of 26 is 2.60. Now, half of that is 1.30. Add both of them and you get 3.90. Same logic can work for a 20% tip, just double to 10%.

Rounding decimals is very similar to rounding other numbers. if the hundredths and thousandths places of a decimal is forty-nine or less, they are dropped and the tenths place does not change. for example, rounding 0.843 to the nearest tenth would give 0.8. , your welcome !