# Sums and Differences of Decimals

Video Solutions to help Grade 6 students learn how to add and subtract multi-digit decimals.

### Lesson 9 Student Outcomes

• Students relate decimals to mixed numbers and round addends, minuends, and subtrahends to whole numbers in order to predict reasonable answers.
• Students use their knowledge of adding and subtracting multi-digit numbers to find the sums and differences of decimals.
• Students understand the importance of place value and solve problems in real-world contexts.

Classwork
Example 1
25 3/10 + 376 77/100
Example 2
426 1/5 - 275 1/2

Exercises 1–5
Calculate each sum or difference.
1. Samantha and her friends are going on a road trip that is 245 7/50 miles long. They have already driven 128 53/100 How much further do they have to drive?

2. Ben needs to replace two sides of his fence. One side is 367 9/100 meters long, and the other is 329 3/10 meters long. How much fence does Ben need to buy?

3. Mike wants to paint his new office with two different colors. If he needs 4 4/5 gallons of red paint and 3 1/10 gallons of brown paint, how much paint does he need in total?

4. After Arianna completed some work, she figured she still had 78 1/200 pictures to paint. If she completed another 34 23/25 pictures, how many pictures does Arianna still have to paint?

Use a calculator to convert the fractions into decimals before calculating the sum or difference.
5. Rahzel wants to determine how much gasoline he and his wife use in a month. He calculated that he used 78 1/3 gallons of gas last month. Rahzel’s wife used 41 3/8 gallons of gas last month. How much total gas did Rahzel and his wife use last month? Round your answer to the nearest hundredth. Example 1
25 3/10 + 376 77/100
Example 2
426 1/5 - 275 1/2

Problem Set
1. Find each sum or difference.
a. 381 1/10 - 214 43/100
b. 32 3/4 - 12 1/2
c. 517 37/50 + 312 3/100
d. 632 16/25 + 32 3/10
e. 421 3/50 - 212 9/10

2. Use a calculator to find each sum or difference. Round your answer to the nearest hundredth.
a. 422 3/7 - 367 5/9
b. 23 1/5 + 45 7/8