First calculate 10 percent of the bill by moving the decimal point one place to the left. Divide that number in half to get 5 percent, then add the two together. For example, 10 percent of a $24.00 bill is $2.40; half of that is $1.20; add them together for $3.60, a 15 percent tip.
The Mental Math Trick for Calculating a Restaurant Tip
Figuring out how much to leave for a tip was a little trickier before there were apps to calculate it for you, but there's an easy way to do it in your head.
Figure 15 Percent in Three Steps
Figure 20 Percent in Two Steps
If you're feeling generous, a 20 percent tip takes only two steps: calculate 10 percent of the bill, then double that number.
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