Subtract by finding the missing part
This idea can make subtraction feel far less daunting for your child, because every addition fact they know becomes a subtraction fact too: 8 + 2 = 10 tells them that 10 - 8 = 2. Counting up is also how people make change with money. In 2nd grade, the same thinking makes problems like 53 - 48 quick: count up 2 to reach 50, then 3 more.
In this video, your child will learn to subtract by thinking of an addition problem.
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
10 − 8 = ?
Example 2
12 − 9 = ?
Your child's turn
13 − 8 = ?
The three key steps
- 1Start at the number you take away.
- 2Count up to the bigger number.
- 3Count how many you add; that's the answer.
Mistakes to listen for
- Counting backward for every problem, even 15 - 13, and losing track, landing on 3 or 1 instead of 2.
- Counting the starting number as a step, saying "8, 9, 10, that's 3" for 10 - 8 instead of 2.
- Treating 10 - 4 as a brand-new problem, without noticing that the well-known fact 6 + 4 = 10 already answers it.
The lesson shows every step, so your child sees why it works. Read our parent's guide to subtracting by finding the missing part →
Is your child ready to practice what they've learned?
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More 1st 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 by finding the missing part, 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 by finding the missing part 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 by finding the missing part
Questions at your child's level, about five minutes a day, on subtracting by finding the missing part and whatever PK-5 skills they need to develop. Unlimited practice, free forever.
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