Subtract within 100
Subtracting is how your child works out how many are left and how much more, and getting comfortable with it makes everyday math feel easier. It leads to subtracting within 1,000 later this year, then to multi-step problems, time, and money in 3rd grade. It also gives your child a way to check their own work, since adding the answer back should lead to where they started. You'll see it when you count change or find out how many pages are left.
In this video, your child will learn to subtract within one hundred.
The lesson stops at each question for your child's answer.
Three problems, each a little harder
Each problem is worked step by step. Your child will solve the last one before Bobby shows how.
Example 1
48 − 31 = ?
Example 2
52 − 27 = ?
Your child's turn
63 − 28 = ?
The three key steps
- 1Start by subtracting the ones.
- 2Not enough? Break a ten.
- 3Then take away the tens.
Mistakes to listen for
- Subtracting the smaller digit from the larger in each place, so 82 - 56 becomes 34.
- Counting back one number at a time and losing track partway, so 53 - 18 ends up a few away from 35.
- Thinking subtraction only means taking away, so a question like "How many more is 64 than 48?" feels like a different kind of problem.
The lesson shows every step, so your child sees why it works. Read our parent's guide to subtracting within 100 →
Is your child ready to practice what they've learned?
Bobby's Math Club offers unlimited practice for free.
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More 2nd grade Numbers & Place Value, with questions your child answers along the way.
Questions parents ask
Does my child need an account to watch?
No. You can watch this on any device at any time. If your child would like to practice subtracting within 100, and you'd like parent-friendly reports on your child's progress and growth, you can join Bobby's Math Club for unlimited free practice.
What happens when my child answers a question?
A right answer gets a cheer, and the lesson carries on. If your child isn't sure, they can tap "I don't know yet", and Bobby gives the answer and shows another example. Nothing is scored or stored.
Is this the same lesson that's on YouTube?
Yes. Here, the lesson stops at each question and waits for your child to answer. On YouTube, each question stays on screen for a few seconds, and then the lesson plays on.
Where can I learn more?
There's a short, kid-friendly lesson like this one for every Pre-K to 5th grade math skill, all in our video library. Our parent's guide to subtracting within 100 has more on where kids get stuck and how you can help at home. In the club, your child practices at just the right level, about five minutes a day, and you get parent-friendly reports as they grow. Learn more about how it works →
Practice subtracting within 100
Questions at your child's level, about five minutes a day, on subtracting within 100 and whatever PK-5 skills they need to develop. Unlimited practice, free forever.
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