Dollars and Decimals - dummies

By Mark Zegarelli

You use decimals all the time when you count money. And a great way to begin thinking about decimals is as dollars and cents. For example, you know that $0.50 is half of a dollar, so this information tells you: 0.5 = 1/2.


Notice that, in the decimal 0.5, the zero at the end is dropped. This practice is common with decimals.

You also know that $0.25 is a quarter — that is, one-fourth of a dollar — so: 0.25 = 1/4.


Similarly, you know that $0.75 is three quarters, or three-fourths, of a dollar, so: 0.75 = 3/4.


Taking this idea even further, you can use the remaining denominations of coins — dimes, nickels, and pennies — to make even more connections between decimals and fractions.


Notice that again the zero in the decimal 0.1 is dropped, but the zeros in the decimals 0.05 and 0.01 are kept. You can drop zeros from the right end of a decimal, but you can’t drop zeros that fall between the decimal point and another digit.

Decimals are just as good for cutting up cake as for cutting up money. This time, you are given the decimals that tell you how much cake you have. Fractions and decimals accomplish the same task: allowing you to cut a whole object into pieces and talk about how much you have.

Cakes cut and shaded into (A) 0.75, (B) 0.4, (C) 0.1, and (D) 0.7.
Cakes cut and shaded into (A) 0.75, (B) 0.4, (C) 0.1, and (D) 0.7.