Adding & Subtracting Decimals
What is the sum: 14.5 + 3.2
17.7
What is the product: 3.2 x 4
12.8
What is the quotient: 8.4 divide 2
4.2
What is the sum: 3/8 + 1/8
4/8 or 1/2
What is the product: 1/2 x 3/4
3/8
What is the difference: 20 - 4.75
15.25
What is the product: 1.5 x 0.6
0.90 or 0.9
What is the quotient: 4.5 divide 0.5
9
What is the difference: 5/6 - 1/3
3/6 or 1/2
What is the product: 2/5 x 5/6
10/30 or 1/3
What is the sum: 105.6 + 9.88
115.48
What is the product: 0.25 x 1.4
0.35
What is the quotient: 1.44 divide 1.2
1.2
What is the difference: 4 1/2 - 1 1/8
3 3/8
What is the product: 2 x 3/5
6/5 or 1 1/5
You have a $25.00 gift card. You buy a snack for $3.50 and a drink for $1.75. How much money is left on your card?
$19.75
A massive new update for your favorite game is 4.5 gigabytes. If you need to download it on 3 different consoles in your house, how many gigabytes will you download in total?
13.5 gigabytes
You bought a multipack of 4 collectible character stickers for $5.20. How much did each individual sticker cost?
$1.30
You spent 1 1/4 hours playing Clash Royale and 2/3 of an hour watching YouTube. How much total time were you on your screen?
1 11/12 hours
You have exactly 3/4 of an hour of screen time left before bed. You spend 1/2 of that time playing Roblox, and the rest on TikTok. What fraction of an hour did you spend playing Roblox?
3/8 of an hour
A student solved 15 - 2.4 and got 1.1. What mistake did they make, and what is the correct answer?
They didn't line up the decimals or add a placeholder zero (they just dropped the 15 down and subtracted the 4 from the 5).
The correct answer is 12.6.
A student solved 4.2 x 1.3 and got 54.6. What is their mistake, and what is the real answer?
They forgot to count the total number of decimal places in the original problem (there are two, so they needed two "jumps").
The correct answer is 5.46.
A student is trying to solve 15 divide 0.3. They slide the decimal on the 0.3 to make it a whole 3, and then divide 15 by 3 to get 5. What rule did they break?
Whatever you do to the outside, you MUST do to the inside! They forgot to slide the invisible decimal on the 15 and add a zero.
The correct answer is 50.
A student solves 3/4 + 1/5 and gets 4/9. Explain exactly what they did wrong and find the correct answer.
They broke the Golden Rule and added straight across the top and bottom instead of finding a common denominator (20). The correct answer is 19/20.
A student tries to solve 1 1/2 x 3/4. They multiply the fractions to get 3/8 and just drop the whole number down, giving a final answer of 1 3/8. Why is this wrong?
You cannot multiply mixed numbers as they are! You must convert them to improper fractions first.
Answer: 9/8 or 1 1/8.