enVision Mathematics Grade 5, Topic 2: Use Models and Strategies to Add and Subtract Decimals
In this unit, your child adds and subtracts decimals to hundredths, lining up place values carefully. They round first to estimate, so 4.86 + 7.1 is about 5 + 7, and a sum near 12 makes sense. Grids and number lines show why the decimal points line up. It builds on the place value unit and leads into multiplying multi-digit whole numbers.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Topic 2?
- Rounding decimals to the nearest whole number or tenth, like 4.86 to 5, to estimate sums and differences. Learn more: Rounding decimals, like 4.68 to 4.7
- Adding and subtracting decimals to hundredths, like 7.1 − 4.86, by lining up the decimal points and checking with an estimate. Learn more about adding and subtracting decimals to hundredths: Adding and subtracting decimals to hundredths · Learn more about multiplying decimals to hundredths · Learn more about dividing decimals to hundredths
Sample questions to try together
These are real questions from our practice. Tap the speaker to hear one read aloud, or the light bulb for a hint, and talk about the answer together.
Question 1 of 3
Amara swam one length of the pool in 18.6 seconds. What is her time to the nearest whole second?
- 20 seconds
- 18 seconds
- 19 seconds
How you can help
- Hand your child a receipt with three or four items. Ask them to round each price to the nearest dollar, estimate the total, then add exactly and compare.
- Give your child a pretend $20 at the store and pick two items, like $6.49 and $8.75. Ask how much change is left, $4.76.
- Time two short races on a phone stopwatch, like 12.4 and 11.85 seconds. Ask your child for the difference, 0.55 seconds, writing 12.40 to help line up the places.
Where kids can get stuck
- Lining up the last digits instead of the decimal points, so 3.4 + 1.25 becomes 1.59, not 4.65.
- Subtracting the smaller digit from the larger in each column, so 7.10 − 4.86 becomes 3.76 instead of 2.24.
- Rounding to the wrong place, giving 4.68 or 5 when asked to round 4.68 to the nearest tenth.
Practice makes perfect
Bobby's Math Club has practice problems that adapt to your child’s level, each with a detailed explanation and an easy-to-follow video, so your child can build confidence in these skills one step at a time.
Words your child will hear
- decimal point
- The dot that separates the whole number from the parts smaller than one.
- tenth
- One of 10 equal parts of a whole, written 0.1 or 1/10.
- hundredth
- One of 100 equal parts of a whole, written 0.01 or 1/100.
- round
- To find the closest tenth, whole number, or other place value.
- estimate
- A close guess found with easier numbers, used to check whether an answer makes sense.
- sum
- The answer to an addition problem.
- difference
- The answer to a subtraction problem.
Ready to build your child’s confidence with adding and subtracting decimals?
In Bobby's Math Club, your child practices these skills at just the right level, with a hint when they need one, a clear explanation after every question, and kid-friendly videos. Unlimited practice is free.
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Written by Robert “Bobby” Barnett
Bobby is an award-winning math teacher, the author of Meet Every Learner’s Needs, and the father of two elementary-school math learners. He uses Bobby’s Math Club with his own kids a few times every week. Learn more or contact Bobby.
Which math standards does enVision Mathematics Grade 5 Topic 2 cover?
enVision Mathematics Grade 5 Topic 2 covers these math standards. Each one links to what it means, sample questions, and teaching strategies.
For teachers: Unit names and order vary between editions and districts, so your school’s own materials have the exact sequence. Learn how Bobby's Math Club can help your students grow.