Decimals
Study Guide
SOLs:
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Name: __________________________
Date: ______________________
5.1: The student, given a decimal through thousandths, will round to the nearest whole number, tenth, or hundredth.
5.2: The student will
o
a) recognize and name fractions in their equivalent decimal form and vice versa;
o
b) compare and order fractions and decimals in a given set from least to greatest and greatest to least.
5.4: The student will create and solve single-step and multistep practical problems involving addition, subtraction, multiplication, and
division with and without remainders of whole numbers.
5.5: The student will
o
a) find the sum, difference, product, and quotient of two numbers expressed as decimals through thousandths (divisors
with only one nonzero digit)
o
b) create and solve practical problems involving decimals.
*Decimals
-A decimal is another way to write a fraction when the denominator is 10, 100, 1,000, and so on.
Thousands
Hundreds
Tens
Ones
6
5
7
7
8
1
9
3
2
Thousandths
Ten
Thousands
3
Hundredths
Hundred
Thousands
1
Tenths
Millions
We use place-value positions to name decimals.
5
9
6
1.29 = one and twenty nine hundredths
Try it!
Write this number in word form:
1,522.37
________________________________________
_____________________________________________________________________________
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*Help in your textbook can be found on page 4-10
*Rounding Decimals
Round this number to the nearest
hundredth.
45.476
Step 1: Find the rounding place. Look at the digit to the right
of the rounding place.
Step 2: If the digit is 5 or more add 1 to the rounding digit. If
45.476
The digit is less than 5, leave the rounding digit alone.
Step 3: Change all the digits to the right of the rounding digit to zeros.
45.480
Try it!
Round to the nearest hundredth:
50.845
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*Help in your textbook can be found on page 26-27.
* Comparing Decimals
Step 1: Line up the decimals points.
Step 2: Compare numbers left to right.
32.456
0.080
32.501
0.800
32.456
0.080
32.501
0.800
32.501 > 32.456
0.800 > 0.080
*Help in your textbook can be found on page 38-41
*Adding & Subtracting Decimals
Step 1: Write the numbers, lining up the decimal points.
Step 2: Add or subtract as usual.
Step 3: Bring down your decimal point in the answer.
*Help in your textbook can be found on page 12-13
0.25
+ 0.37
0.75
- 0.36
1
0.25
+ 0.37
2
15
0.75
- 0.36
9
1
0.25
+ 0.37
0.6 2
15
0.75
- 0.36
0.3 9
*Multiplying Decimals
Step 1: Write the numbers, but DO NOT line up the decimal points.
2.56
X 25
11
23
2.56
X 25
1280
+5120
6400
Step 2: Multiply as usual.
Step 3: Count the decimal places in both factors.
Move the decimal point this many places in your answer.
2.56 -2 decimal places
X 25 -0 decimal places
1280
+5120
64.00 -2 decimal places
*Help in your textbook can be found on page 88-89
*Dividing Decimals
Step 1: Write the numbers, and write the decimal point in
the quotient directly above the decimal point in the dividend.
Step 2: Divide as usual.
16
16
*Help in your textbook can be found on page 230 -237
*Decimals as Fractions
Word names for decimals will help you write decimals as fractions.
0.8 is said “eight tenths” = 8
10
0.45 is said “zero and forty-five hundredths” = 45
100
0.785 is said “zero and seven hundred and eighty-five thousandths” = 785
1000
1.045 is said “one and forty-five thousandths” =
*Help in your textbook can be found on page 426-427.
1
45
1000
.
2.40
0 .15
2.40
-16
80
-80
0