Add & Subtract Decimals
Question:
What is:
3.7 + 2.45
6.15
What is:
2.5 × 4
10
Question:
What is:
6.4 ÷ 2
Answer: 3.2
Question:
Mia has $20.00 and spends $7.65.
How much money does she have left?
$12.35
Question:
A student says:
4.5 + 2.37 = 6.87
Is the student correct?
Answer: Yes!
4.50 + 2.37 = 6.87
Question:
What is:
3.7 + 2.45
4.72
Question:
What is:
2.5 × 4
18
Question:
What is:
8.4 ÷ 4
2.1
Question:
A backpack costs $18.75. How much would 4 backpacks cost?
$75.00
Question:
A student says:
7.2 − 3.85 = 4.55
Do you agree?
Answer: No.
Line up the decimal points:
7.20 − 3.85 = 3.35
The correct answer is 3.35.
Question:
What is:
8.42 − 3.7
23.585
Question:
What is:
4.25 × 20
85
Question:
What is:
7.2 ÷ 0.6
12
A recipe requires 2.5 kilograms of flour. You already have 750 grams.
How many kilograms of flour do you still need?
Answer: 1.75 kilograms
750 g = 0.75 kg
2.5 − 0.75 = 1.75 kg
Question:
A student says:
5.4 × 20 = 10.8
Find the mistake and give the correct answer.
Answer: The student multiplied by 2 instead of 20.
5.4 × 2 = 10.8
But:
5.4 × 20 = 108
Correct answer: 108
A water tank contains 24.5 liters of water. A scientist removes 8.75 liters and then adds 3.6 liters.
How much water is in the tank now?
Answer: 19.35 liters
24.5 − 8.75 = 15.75
15.75 + 3.6 = 19.35
What is:
2.35 × 300
Answer: 705
2.35 × 3 = 7.05
Then multiply by 100:
7.05 × 100 = 705
Question:
A pitcher contains 6.3 liters of juice. Each serving is 0.3 liters.
How many servings can be made?
Answer: 21 servings
6.3 ÷ 0.3 = 21
Question:
A runner completes 5 laps. Each lap is 0.8 kilometers.
How many kilometers does the runner travel altogether?
Answer: 4 kilometers
0.8 × 5 = 4
Question:
A student says:
3.6 ÷ 0.6 = 0.6
Do you agree? Explain.
Answer: No.
Think:
0.6 × ? = 3.6
Since:
0.6 × 6 = 3.6
the answer is:
3.6 ÷ 0.6 = 6
Question:
A student calculates:
30.2 − 7.85 + 4.607 = 27.057
Is the student correct? Find the correct answer.
Question:
A student calculates:
30.2 − 7.85 + 4.607 = 27.057
Is the student correct? Find the correct answer.
Answer: No.
First:
30.200 − 7.850 = 22.350
Then:
22.350 + 4.607 = 26.957
Correct answer: 26.957
Question:
A store sells notebooks for $2.75 each. A teacher buys 24 notebooks.
How much does she spend?
Answer: $66
2.75 × 24 = 66
Question:
A number is divided by 300 and the answer is 0.024.
What was the original number?
Answer: 7.2
Because:
0.024 × 300 = 7.2
Question:
A baker has 12.5 kilograms of flour. She uses 3.75 kilograms to make bread and 2.8 kilograms to make cookies.
She divides the remaining flour equally among 3 large containers.
How many kilograms of flour go into each container?
Answer: 1.983⅓ kilograms per container
First:
12.5 − 3.75 = 8.75
Then:
8.75 − 2.8 = 5.95
Finally:
5.95 ÷ 3 = 1.983⅓ kilograms
Question:
A student has $50.
They spend $12.75 on a book and $8.50 on a game. Then they split the remaining money equally between 3 savings jars.
How much money goes into each jar?
Answer: $9.583⅓ per jar
First find the total spent:
$12.75 + $8.50 = $21.25
Money remaining:
$50 − $21.25 = $28.75
Divide equally:
$28.75 ÷ 3 = $9.583⅓
Answer: $9.583⅓ per jar