Find the missing number
Solving a missing-number puzzle shows your child that they can reason their way to an answer, not only calculate one. It means seeing how three numbers fit together, which is exactly the thinking behind checking subtraction with addition. In 2nd grade the same puzzles use numbers up to 100, and in middle school the box becomes a letter: 8 + x = 11 is the same question your child is answering now.
In this video, your child will learn to find missing numbers in adding and subtracting.
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
8 + ? = 11
Example 2
5 = ? − 3
Your child's turn
? − 4 = 9
The two key steps
- 1To find a missing part, count up.
- 2To find the first number, put back what was taken away.
Mistakes to listen for
- Adding the two numbers they see wherever the box is, so 8 + ? = 11 gets 19 instead of 3.
- Subtracting 3 from 5 to get 2 for ? - 3 = 5, when the missing number is really 8.
- Freezing when an equation starts with the single number, like 5 = ? - 3, because it looks unfamiliar.
The lesson shows every step, so your child sees why it works. Read our parent's guide to missing numbers, like 8 + ? = 11 →
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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 missing numbers, like 8 + ? = 11, 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 missing numbers, like 8 + ? = 11 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 →
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