Decimals

Decimal Places

On the GED math test you will need to know how to read and work with decimals. Decimals, like fractions, are used to express number values less than 1.  Whole numbers are placed to the left of a decimal point and the places to the right of a decimal point are called decimal places. For example you can write the number 1 as 1 or 1.0.

1 is equal to 1.0 since only a zero after the decimal point does not change a value. On the other hand if you wanted to write one and a half, or , as a decimal, you would write 1.5.

0.5 is equal to one half because 5 is half of 10 and each digit is counted in tens.

When you say a number with a decimal, you say tenths for the first decimal place, hundredths for the second and so on. So you could say 1.5 as one and five tenths, and you could say 1.05 as one and five hundredths. The table below provides the names for all the digits you will need to know for the GED math test. Also included for your reference are the names for the whole number digits (those to the left of the decimal).

The example number in the table above is 526.74, which would be read as “five hundred twenty-six and seventy-four hundredths.” Note that although there are 7 tenths you only say the value of the smallest decimal place, in this example “hundredths.” Also note that the decimal point is read as “and.”

Zeros and Decimals

Zeros have a different effect on decimals than on whole numbers. A zero to the left of a whole number, for example 2, does not change its value, since 02 = 2. However, a zero to the right of a whole number increases that number’s value by ten, since 20 = 2 x 10. On the other hand, a zero to the left of a decimal value (and to the right of the decimal point) reduces the value of that decimal by 10, since .02 = .2 divided by ten. A zero to the right of a decimal value does not change its value.

Comparing and Ordering Decimals

Because the values of decimals are affected differently by placement of digits, comparing and ordering decimals can sometimes be difficult for GED math students. For example .3 might at first look smaller than .089477, even though .3 is more than 3 times as large as .089477. What you can do when asked to compare or order fractions on the GED math test is to make sure the two numbers you are comparing have the same number of digits. So in the example above you would change .3 to 300,000 and change .089477 to 089,477. Clearly now 300,000 is larger than 89,477.

More information about using decimals:
Adding & Subtracting Decimals
Multiplying Decimals
Dividing Decimals
Converting Decimals to Fractions and Fractions to Decimals

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6 comments

  1. CatreshaP. says:

    Having problems with common conversions,help??!! At the market,a man buys six avacodos for$ 13.35.All produce is 30% off today only.How much will two avacados cost you tomorrow at a full price? Need to know why is my answer$5.00 ;reg $ 2.50??

    • Ziyi says:

      Since you’re dealing with two different amounts of avocados, 6 and 2 for the second day, you should first find out the price of one avocado on each day. So day one 6 avocados is 13.35, since 13.35 divided by 6 is 2.225, one avocado costs $2.22 and one half of a penny. Now that price is 30% off and we need to know the full price for the second day. Since it’s 30% off, you’re paying 70% of the regular price so you set up the equation .7 / 2.225 = 1 / x . Then you cross multiply. Check this http://www.math4ged.com/word-problems-with-percents/ for a video on how to do that. You’ll get about 3.18 for the regular price of one avocado. Now since you want to buy 2 just multiply by two and the answer is $6.36

  2. Catresha says:

    Oh ,and thanks for the encouragement :0) ! Will stay confident !

  3. CatreshaP. says:

    Hi 🙂 ‘ just want to say thanks for showing me exactly what I was,nt seeing in the problem I sent you.My weaknesses are what you pointed out,fractions,crossmultiplying,how to find x ;settingup to solve a word problem. Just need a push ! Thanks,will keep studying 🙂

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