Bridges in Mathematics Grade 3, Unit 3: Multi-Digit Addition & Subtraction
In this unit, your child adds and subtracts numbers up to 1,000 using place value, the value a digit has because of where it sits. They round to the nearest 10 or 100 to estimate, then check that exact answers make sense. After a stretch of multiplication, this unit returns to bigger numbers before measurement and fractions come next.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 3?
- Rounding numbers like 347 to 350 or 300 to make an estimate, a quick close guess, before solving. Learn more: Rounding to the nearest 10 or 100
- Adding and subtracting three-digit numbers by hundreds, tens, and ones, including regrouping, trading 10 ones for 1 ten. Learn more about adding within 1,000: Adding within 1,000 · Learn more about subtracting within 1,000
- Solving two-step problems with bigger numbers, such as finding the pages left after reading on two different days. Learn more: Story problems with two steps
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
- Round prices on a grocery receipt to the nearest ten, such as $38 to $40 and $24 to $20, and add them for an estimate ($60) before checking the exact total ($62).
- Ask how many pages are left in a book your child is reading, such as a 312-page book where they are on page 175, and let them explain their method (137).
- Keep score in a board game and ask your child how far ahead one player is, such as 452 points against 287 (165 points).
Where kids can get stuck
- Subtracting the smaller digit from the larger in every column, so 503 − 267 comes out as 364 instead of 236.
- Forgetting the regrouped ten or hundred when adding, so 456 + 278 comes out as 624 instead of 734.
- Looking at the wrong digit when rounding, so 347 to the nearest hundred becomes 400 instead of 300.
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 of a digit because of where it is in a number.
- round
- To change a number to a nearby number that is easier to use.
- estimate
- A number close to the exact answer that you find quickly.
- regroup
- To trade 10 ones for 1 ten, or 10 tens for 1 hundred, and back.
- sum
- The answer to an addition problem.
- difference
- The answer to a subtraction problem.
- hundreds
- The place three spots from the right in a number, worth groups of 100.
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.
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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 Bridges in Mathematics Grade 3 Unit 3 cover?
Bridges in Mathematics Grade 3 Unit 3 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.