Fluently subtract within 20
If subtraction facts come easily, your child can focus on what a problem is asking instead of counting backward. Facts like 15 - 7 sit inside bigger problems this year, such as 65 - 27. They're also how your child works out how many are left in a pack, how many points a team still needs, or how many days remain until the weekend. Each fact they know saves time on every bigger problem that uses it.
In this video, your child will learn to subtract within twenty quickly, in your head.
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
13 − 4 = ?
Example 2
15 − 7 = ?
Your child's turn
16 − 9 = ?
The three key steps
- 1Split the number you take away.
- 2Take away down to 10 first.
- 3Then take away the rest.
Mistakes to listen for
- Counting back by ones for 15 - 7, which is slow and easy to lose track of, so the answer comes out 7 or 9.
- Racing through facts like 17 - 3 but slowing to a crawl on ones that cross ten, like 13 - 7 or 12 - 5.
- Knowing 9 + 5 = 14 by heart without noticing that the same fact answers 14 - 9 and 14 - 5.
The lesson shows every step, so your child sees why it works. Read our parent's guide to subtracting fluently within 20 →
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 Problem Solving, 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 fluently within 20, 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 fluently within 20 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 fluently within 20
Questions at your child's level, about five minutes a day, on subtracting fluently within 20 and whatever PK-5 skills they need to develop. Unlimited practice, free forever.
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