Part of being an efficient consumer is being aware of percentages. From sales tax to restaurant tips, you need to be aware of how to calculate and estimate percentages. Percent comes from the Latin Per Centum, which means “out of one hundred”. Thus a percentage (1%) is a hundredth of a number (1/100). You might have noticed that 50% is one-half (1/2) and 10% is one-tenth (1/10) and 20% is two-tenths (2/10) or equivalently, one-fifth. Imagine that you did not have a calculator and you needed to calculate the following: A 15% tip on a $88 bill 8% sales tax on an item that costs $25 A 28% income tax on a $50,000 income Explain how you would calculate (or at least estimate) each of these values without using a calculator. Can you estimate these in your head?