Reveal Math Grade 2, Unit 6: Two-Digit Subtraction
In this unit, your child subtracts two-digit numbers within 100. They count up, break numbers apart by tens and ones, and regroup a ten as ten ones when needed. They also subtract 10 or 100 in their heads and explain why their methods work. It builds on two-digit addition and leads into three-digit addition next.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 6?
- Subtracting within 100, like 62 - 28, by counting up, breaking apart numbers, or regrouping 1 ten as 10 ones. Learn more about adding within 100: Adding within 100 · Learn more about subtracting within 100
- Taking away 10 or 100 in their heads, like knowing 10 less than 305 is 295, and noticing which digits change. Learn more: Adding or taking away 10 or 100 mentally
- Explaining why a subtraction strategy works, such as why 62 - 30 + 2 gives the same answer as 62 - 28. 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 10 + 25 + 5?
- 30
- 40
- 45
How you can help
- Count up to subtract at the store: if you have 62¢ and spend 28¢, count from 28 to 30, then to 60, then to 62. Add the jumps to find what is left.
- Ask 'What's 10 less? What's 100 less?' using a number you see on a walk, like 305. Talk about what happens when the tens digit is zero.
- When your child solves a subtraction problem, ask them to check it by adding. If 62 - 28 = 34, then 34 + 28 should make 62.
Where kids can get stuck
- Subtracting the smaller digit from the larger, so 62 - 28 becomes 46 instead of 34.
- Subtracting 30 instead of 28, then taking away 2 more instead of adding 2 back.
- Getting stuck finding 10 less than 305, because the tens digit is zero.
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
- difference
- The answer when you subtract. In 13 - 5 = 8, the difference is 8.
- regroup
- To trade 10 ones for 1 ten, or 10 tens for 1 hundred, and back again.
- count up
- Subtracting by counting from the smaller number up to the bigger one.
- tens digit
- The digit in the tens place. In 62, the tens digit is 6.
- strategy
- A plan or way to solve a problem.
- subtract
- To take away, or to find how far apart two numbers are.
Ready to build your child’s confidence with subtracting within 100?
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 Reveal Math Grade 2 Unit 6 cover?
Reveal Math Grade 2 Unit 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.