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### Course: Kindergarten>Unit 2

Lesson 3: Making 10

Sal finds out how many bananas we need to add to 3 bananas to make 10 bananas. Created by Sal Khan.

## Want to join the conversation?

• Do you have to add only numbers? Or can you add real bananas too?
• You can add anything. Bananas can each represent a number.
• Can you turn around facts like 3+4=7; 4+3=7?
• Yes! You sure can, if you have the same numbers it would turn out to be the same answer.
• Couldn't you just do 10-3=7?
• Yes you can because you're using at least one operation,three numbers,and one equal sign.
• If I add 7+10, would it be the same as 7x10?
• no but doing 7+7 ten times would the same as 7x10

## Video transcript

- [Voiceover] We've got three bananas here. One, two, three. So I'm starting with three bananas and I want to add some number of bananas so that I end up with 10 bananas. So this is what I'm starting with. I'm starting with three and I want to end up with 10. One, two, three, four, five, six, seven, eight, nine, ten. So what do I have to add to the three to get to 10? I encourage you to pause this video and try this out on your own. So let's work through this. So let's just start adding bananas. So that's three. So now let me add a fourth. That would be my fourth banana. Five bananas. Six bananas. Seven bananas. Eight bananas. Nine bananas. And ten bananas. So how many bananas did I add? So now I added some number of bananas here. So in total I have one, two, three, four, five, six, seven, eight, nine, ten. So how many did I have to add to the three in order to get to the total of 10 in order to get this 10 right over here? We could just count these. This is one, this is two, this is three, four, five, six, seven. I added seven bananas. I added seven bananas to the original three bananas to get to 10. So three plus seven is equal to 10. And you can see that what we have on this left side is indeed equal to what we have on the right side. On the left side we have one, two, three, four, five, six, seven, eight, nine, ten bananas and on the right hand side we have one, two, three, four, five, six, seven, eight, nine, ten. So they are indeed equal.