Decimals

Decimals

• Comparing• Adding • Subtracting• Multiplying• Dividing

Comparing Decimals

• Which is the largest number?.02 .0201 .021

Which is the largest number?.02 .0201 .021

The easiest way to tell is to line them up vertically with the decimals over one another

.02.0201.021

Which is the largest number?.02 .0201 .021

And then add zeroes until they all have the same number of digits.0200.0201.0210

Now, If you read them ignoring the initial zeroes, it should be obvious which is the biggest

- .0210 (which would read two-hundred-ten)

Place in order from least to greatest:

• 6.4 6.388 6.41

Place in order from least to greatest:

• 6.4 6.388 6.41

6.400 Six-thousand four-hundred

6.388 Six-thousand three-hundred eighty-eight

6.410 Six-thousand four-hundred ten

So, in order, they would be:

In order from least to greatest:

6.388 6.4 6.41

Order from least to greatest:

• 0.001 0.00102 0.0011

0.001 0.00102 Step one – line up vertically 0.0011 -------------- 0.00100 0.00102 Step two – add zeroes 0.00110

0.00100 0.00102 Step 3 - Compare 0.00110• 100, 102 and 110• These numbers are already in order from least

to greatest

Adding Decimals

• To add decimals simply line them up vertically with the decimals over one another, bring the decimal straight down into the answer line, and then add as usual.

• Example: 5.321 + 2.397 5.321+2.397 7.718

Subtracting Decimals

• To subtract decimals simply line them up vertically with the decimals over one another, bring the decimal straight down into the answer line, and then subtract as usual.

• Example: 0.45 - 0.28

Again, it’s just the same as non-decimal numbers. Just make sure the decimals are lined up over one another

and that you bring it straight down.

3 15

0.45- 0.28_ 0.17

Multiplying Decimals

• Get rid of unnecessary zeroes• Count the number of digits to the right of the

decimal in the whole problem• Ignore the decimal and solve• Give your answer the same number of digits to

the right of the decimal point as the TOTAL number of digits to the right of the decimal in the problem

• Example: 0.25 x 3.80

• Get rid of unnecessary zeroes:0.25 x 3.80 .25 x 3.8• Count digits:There are three digits total to the right of the decimal

in the problem. (2, 5, and 8)• Ignore decimals and multiply

1 4 25x 38 200

+ 75 950


• Give your answer the same number of digits to the right of the decimal point as the TOTAL number of digits to the right of the decimal in the problem

950Three digits to the right of the decimal, so: .950 .95


• Example 26.28 x 2.5


• Example 26.28 x 2.5

There are no zeroesThere are 3 digits to the right of the decimal 628x 25 31401256__15700 15.700 15.7

Dividing Decimals

• Dividing decimals by whole numbers:• Simply bring the decimal straight up and then

ignore it. Add zeroes to the end of the divisor if necessary to avoid a remainder.

• Example 40.24 ÷ 5

Dividing Decimals

40.24 ÷ 5

Dividing Decimals• Non-terminating decimals are decimals that

keep going without ever getting to a stopping point. Try dividing 100 by 30.

• The way to show that a decimal doesn’t stop is

to draw a line above the decimal digit that continues to repeat. 100 ÷ 30 =

Dividing Decimals By Decimals

Dividing Decimals By Decimals

• Another Example:2.604 ÷ 8.4

• Do the decimal practice worksheet on page 113 of your book, and check your answers against the answer key posted on BB.

• Do pages 7-10 in the GED Practice Packet, and then fill in the answer sheet on BB to get feedback.

Documents

Decimals