Margie saw this sale sign in the clothing department. What is another way to write three dollars? Here we show two ways to write three dollars: $3. $3...
California Mathematics Content Standards REFRESHER LESSON
5.NS 2.0, 2.1 Add, subtract, multiply, and divide with decimals; add with negative integers; subtract positive integers from negative integers; and verify the reasonableness of the results.
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• Adding and Subtracting Decimal Numbers and Whole Numbers Refresher Concept Margie saw this sale sign in the clothing department. What is another way to write three dollars?
T-shirt close-out $3 each
Here we show two ways to write three dollars: $3
$3.00
We see that we may write dollar amounts with or without a decimal point. We may also write whole numbers with or without a decimal point. The decimal point follows the ones place. Here are several ways to write the whole number three: 3
3.
3.0
3.00
As we will see in the following examples, it may be helpful to write a whole number with a decimal point when adding and subtracting with decimal numbers.
Example 1 Paper used in school is often 11 inches long and 8.5 inches wide. Find the perimeter of a sheet of paper by adding the lengths of the four sides. When adding decimal numbers, we align decimal points so that we add digits with the same place values. The whole number 11 may be written with a decimal point to the right. We line up the decimal points and add. The perimeter is 39.0 inches. 11. 8.5 11. + 8.5 39.0
Example 2 Subtract: 12.75 − 5 We write the whole number 5 with a decimal point to its right. Then we line up the decimal points and subtract. 12.75 − 5. 7.75
Refresher Practice
Simplify: a. 4 + 2.1 6.1
b. 4.3 − 2 2.3
c. 3 + 0.4 3.4
d. 43.2 − 5 38.2
e. 0.23 + 4 + 3.7 7.93
f. 6.3 − 6 0.3
g. 12.5 + 10 22.5
h. 75.25 − 25 50.25
i. At the grocery store, paper towels were on sale for $1.89, paper plates were $1.72, and plastic forks were $3. What would be the total for these items? $6.61 j. Morguhn had $20 to spend at the movies. If a child’s ticket was $4.50, how much money did he have left? $15.50
