Go Math! Grade 2, Chapter 5: 2-Digit Subtraction
In this unit, your child subtracts two-digit numbers. They break numbers apart, count up on a number line, and regroup a ten as 10 ones when there are not enough ones. They check answers with addition, explain why their steps work, and solve subtraction story problems. Next comes three-digit adding and subtracting with the same ideas.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Chapter 5?
- Solving subtraction story problems, including comparing amounts, by modeling the story and writing a number sentence. Learn more: One- and two-step story problems within 100
- Subtracting two-digit numbers by breaking apart, counting up, or regrouping a ten, as in 52 − 27 = 25. Learn more about adding within 100: Adding within 100 · Learn more about subtracting within 100
- Explaining why regrouping in subtraction works and checking each answer by adding. 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
- Ask how many pages are left from page 37 to the end of a 62-page story book, and let your child count up by tens and ones.
- Make up compare stories on a walk: "That tree is 45 steps away and the gate is 72. How many more steps to the gate?"
- Ask your child to check a subtraction answer by adding it back, and to tell you what to do if the numbers don't match.
Where kids can get stuck
- Taking the smaller ones digit from the larger, so 52 − 27 becomes 35 instead of 25.
- Regrouping when it isn't needed, as in 68 − 23, and getting tangled in extra steps.
- Adding in a compare story because it says "more," instead of finding the difference.
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.
- difference
- The answer when you subtract; it also tells how much more one amount is.
- break apart
- Splitting a number into parts, like 47 into 40 and 7, to make it easier to use.
- count up
- Subtracting by counting from the smaller number up to the larger one.
- tens
- Groups of 10. In 47, the 4 means 4 tens, or 40.
- ones
- Single units. In 47, the 7 means 7 ones.
- check
- To make sure an answer is right, such as adding back after subtracting.
- number line
- A line with numbers in order at equal spaces, used to count, add, and subtract.
Ready to build your child’s confidence with subtracting 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 5 cover?
Go Math! Grade 2 Chapter 5 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.