Go Math! Grade 2, Chapter 6: 3-Digit Addition and Subtraction
In this unit, your child adds and subtracts three-digit numbers. They break apart numbers by place value, regroup ones, tens, and hundreds, and handle zeros, like in 405 − 128. They also find 10 or 100 more or less in their head and explain why their method works. Next, the year turns to money and time.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Chapter 6?
- Adding and subtracting three-digit numbers by place value, regrouping tens and hundreds and handling zeros, as in 405 − 128. Learn more about adding within 1,000: Adding within 1,000 · Learn more about subtracting within 1,000
- Finding 10 more, 10 less, 100 more, and 100 less than a three-digit number without counting. Learn more: Adding or taking away 10 or 100 mentally
- Explaining why their place value steps work, using quick pictures of hundreds, tens, and ones. Learn more about explaining why addition strategies work: Explaining why addition strategies work · Learn more about explaining why subtraction strategies work
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
A toy store had 450 toy cars and sold 120 of them. How many toy cars are left?
- 320
- 570
- 330
How you can help
- Add the prices of two toys from a flyer, like 128 and 245, and ask your child to add the hundreds, tens, and ones.
- Play "Change One Digit" on a walk: you say 547, and your child gives 10 more, 10 less, 100 more, and 100 less.
- Ask your child to explain their steps for 405 − 128 out loud, and listen for the hundred that turned into tens.
Where kids can get stuck
- Struggling to subtract from a zero, as in 405 − 128, where a ten must come from the hundreds first.
- Writing column totals side by side, so 256 + 378 becomes 51214 instead of 634.
- Counting on by tens to find 100 more and losing count partway.
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
- hundreds
- Groups of 100. In 706, the 7 means 7 hundreds, or 700.
- regroup
- Trading 10 ones for 1 ten, or 1 ten for 10 ones, to add or subtract.
- break apart
- Splitting a number into parts, like 47 into 40 and 7, to make it easier to use.
- place value
- The value a digit has because of its spot in a number: ones, tens, or hundreds.
- mentally
- In your head, without writing it down or using objects.
- sum
- The answer when you add numbers together.
- difference
- The answer when you subtract; it also tells how much more one amount is.
Want to help your child master three-digit addition and subtraction?
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 Go Math! Grade 2 Chapter 6 cover?
Go Math! Grade 2 Chapter 6 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.