It’s easy to calculate a tip without a calculator
Assuming you want to tip 20 percent for good service , move on the decimal point one digit to the left and then double that number. It’s that easy! For example, if a bill is for $35.50, you move the decimal to the left, which gives you $3.55. Double that number, and you’ve got $7.10—a 20 percent tip calculated in seconds.
