Grade 3 • Decimals
Some grade 3 decimals questions look simple at first, but this is exactly where many parents get stuck. The numbers are not always the real problem. The real problem is figuring out what the question is actually asking and how to explain it clearly without making your child more confused.
These challenging decimals problems are written for parents helping children around ages 8 to 9. They go a little beyond normal classwork, so your child has to think harder and you have to teach with more care.
If you have ever said, “I know the answer, but I do not know how to explain it,” this page is for you.
Children at Grade 3 often know the basic skill, but they still struggle when the question hides the important step inside a story, comparison, or extra detail.
Parents usually get stuck because modern classroom questions ask for reasoning, not just a final number. A child may need to show a model, explain a choice, or solve in more than one step.
With decimals, the biggest gap is often place value with money and measurement. That is why these problems feel hard even when the numbers themselves do not look extreme.
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A notebook costs 2.95 dollars and a ruler costs 6.80 dollars. How much do they cost altogether?
Leo had 6.80 dollars and spent 3.40 dollars. How much money did he have left?
A rope is 9.75 metres long. Another rope is 10.25 metres long. What is their total length?
Which is greater: 5.4 or 6.8?
A bottle holds 2.50 litres of juice. 2.45 litres are poured out. How much juice remains?
A runner completed 1.35 km in the first lap and 1.45 km in the second lap. How far did the runner travel in total?
A packet weighs 3.6 kg and another weighs 3.06 kg. Which one is heavier, and by how much?
A shop sells ribbon in pieces of 0.25 m. If a craft group buys 4 equal pieces, how much ribbon do they get?
A child saved 4.75 dollars in week one and 2.40 dollars in week two. How much was saved altogether?
A plant grew 0.85 cm on Monday, 0.65 cm on Tuesday, and 0.90 cm on Wednesday. How much did it grow in total?
A notebook costs 2.95 dollars and a ruler costs 6.80 dollars. How much do they cost altogether?
Answer: 9.75 dollars
How to explain it: If your child starts lining up digits instead of decimal points, switch to cents first to make the structure clearer.
Leo had 6.80 dollars and spent 3.40 dollars. How much money did he have left?
Answer: 3.40 dollars
How to explain it: Children often do better when they hear the money in words: dollars and cents, not just “decimal numbers.”
A rope is 9.75 metres long. Another rope is 10.25 metres long. What is their total length?
Answer: 20.00 metres
How to explain it: Measurement contexts help children see that decimals are not abstract. They describe real lengths and amounts.
Which is greater: 5.4 or 6.8?
Answer: 6.8 is greater
How to explain it: A common mistake is thinking 3.8 is smaller than 3.24 because 24 is bigger than 8. Keep the place values lined up.
A bottle holds 2.50 litres of juice. 2.45 litres are poured out. How much juice remains?
Answer: 0.05 litres
How to explain it: Showing trailing zeros can be really helpful for children who still need to see each place value clearly.
A runner completed 1.35 km in the first lap and 1.45 km in the second lap. How far did the runner travel in total?
Answer: 2.80 km
How to explain it: This is a nice example of regrouping inside decimal addition. Children often need to see that tenths and hundredths can regroup too.
A packet weighs 3.6 kg and another weighs 3.06 kg. Which one is heavier, and by how much?
Answer: 3.60 kg is heavier by 0.54 kg
How to explain it: Rewriting 3.6 as 3.60 helps children understand that zeros can keep place value clear without changing the number.
A shop sells ribbon in pieces of 0.25 m. If a craft group buys 4 equal pieces, how much ribbon do they get?
Answer: 1.00 m
How to explain it: Quarter-dollar and quarter-metre examples help children see friendly decimal amounts more clearly.
A child saved 4.75 dollars in week one and 2.40 dollars in week two. How much was saved altogether?
Answer: 7.15 dollars
How to explain it: If children rush, they sometimes treat 4.75 like 475. Make them name the place values aloud.
A plant grew 0.85 cm on Monday, 0.65 cm on Tuesday, and 0.90 cm on Wednesday. How much did it grow in total?
Answer: 2.40 cm
How to explain it: Breaking a three-number decimal question into two smaller additions lowers stress and reduces place-value mistakes.
Start with the full guide
If you want the broad explanation before the harder practice, open the main parent guide first.
decimals for grade 3Keep exploring this topic
They are written slightly above standard classroom practice, so children must explain their thinking, choose the right steps, and apply the skill in realistic situations.
Start by restating the problem in simpler words, ask what information matters, and guide your child one step at a time instead of solving the whole question at once.
Yes. They work well for stretch practice at home, especially when a child already understands the basics and needs harder examples that build confidence and reasoning.
Cover part of the question, identify the first small step, and write down what is already known before trying to solve the whole problem.
Yes. AceWorksheet gives step-by-step explanations that help parents understand the method first, so they can teach more calmly and clearly at home.
AceWorksheet
AceWorksheet gives parents AI-powered step-by-step explanations for tricky homework questions, so you can spend less time guessing and more time teaching with confidence.
