Go Math! Grade 2, Chapter 4: 2-Digit Addition
In this unit, your child adds two-digit numbers. They break numbers apart into tens and ones, regroup 10 ones as 1 ten, and record the steps on paper. They add three and four numbers at once, explain why their method works, and solve addition story problems. Two-digit subtraction comes next, using the same tens-and-ones ideas.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Chapter 4?
- Solving addition story problems within 100 by drawing a model and writing a number sentence. Learn more: One- and two-step story problems within 100
- Adding two-digit numbers by breaking apart tens and ones or by regrouping on paper, as in 47 + 38 = 85. Learn more about adding within 100: Adding within 100 · Learn more about subtracting within 100
- Adding three or four two-digit numbers, grouping numbers that make a ten to keep it simple. Learn more: Adding up to four two-digit numbers
- Explaining why breaking apart or regrouping works, using quick pictures of 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
What is 80 minus 20?
- 50
- 60
- 70
How you can help
- Add up two prices at the store, such as 36¢ and 45¢, and ask your child to talk you through the tens and ones.
- Keep score in a family game and have your child add each round, regrouping when the ones make 10 or more.
- Ask your child to teach you how they added 29 + 34, using lines for tens and dots for ones.
Where kids can get stuck
- Forgetting to add the regrouped ten, answering 53 for 29 + 34 instead of 63.
- Adding four numbers left to right and missing easy pairs, like 36 and 14 making 50.
- Writing all of 12 in the ones place, so 35 + 27 becomes 512.
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
- regroup
- Trading 10 ones for 1 ten, or 1 ten for 10 ones, to add or subtract.
- tens
- Groups of 10. In 47, the 4 means 4 tens, or 40.
- ones
- Single units. In 47, the 7 means 7 ones.
- addend
- Each number being added. In 5 + 3 = 8, the addends are 5 and 3.
- sum
- The answer when you add numbers together.
- break apart
- Splitting a number into parts, like 47 into 40 and 7, to make it easier to use.
- number sentence
- Numbers and symbols that show a math idea, like 8 + 7 = 15.
Want to help your child master adding two-digit numbers?
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 4 cover?
Go Math! Grade 2 Chapter 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.