Math Expressions Grade 3, Unit 4: Multidigit Addition and Subtraction
In this unit, your child adds and subtracts numbers up to 1,000, using place value to break numbers into hundreds, tens, and ones and to regroup. Children also round to the nearest 10 or 100 to estimate and check. It follows the measurement and graphs unit, and the next unit uses these skills to write equations for word problems.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 4?
- Rounding three-digit numbers to the nearest 10 or 100, such as 685 to 690 or 700, to estimate sums and differences. Learn more: Rounding to the nearest 10 or 100
- Adding and subtracting three-digit numbers with regrouping, or trading 1 hundred for 10 tens, even when subtracting across zeros. Learn more about adding within 1,000: Adding within 1,000 · Learn more about subtracting within 1,000
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
What is 43 rounded to the nearest 10?
- 50
- 40
- 30
How you can help
- Keep score in a board or card game up to 1,000, adding each round's points out loud and checking the running total with a quick estimate.
- Ask how many more: if a puzzle has 500 pieces and 263 are in place, how many are left to go? Check by adding the two parts back together.
- Pick a three-digit number from a sign, a receipt, or a license plate, such as 685, and round it to the nearest 10 and to the nearest 100.
Where kids can get stuck
- Forgetting the regrouped hundred, so 365 + 482 comes out as 747 instead of 847.
- Getting tangled when subtracting across zeros, as in 500 - 263, and skipping a trade from the hundreds.
- Rounding every number that ends in 5 down, such as 65 to 60 instead of 70.
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
- place value
- The value a digit has because of its place, like the 4 in 470 meaning 4 hundreds.
- hundreds
- The place that tells how many groups of 100 are in a number.
- tens
- The place that tells how many groups of 10 are in a number.
- ones
- The place that tells how many single units are in a number.
- regroup
- To trade 10 ones for 1 ten, or 10 tens for 1 hundred, and back.
- round
- To change a number to a nearby, friendlier number, like 47 to 50.
- estimate
- A close guess, often made by rounding, to check whether an answer makes sense.
- sum
- The answer to an addition problem.
- difference
- The answer to a subtraction problem.
Want to help your child master adding and subtracting to 1,000?
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.
Join the club
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 Math Expressions Grade 3 Unit 4 cover?
Math Expressions Grade 3 Unit 4 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.