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Getting to 10 by filling boxes

Sal shows how to add two numbers to make 10. He uses 3 + ___ = 10 and 6 + ___ = 10 as examples.

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Video transcript

- [Voiceover] We have three plus blank is equal to 10. So pause the video and try to figure out what the blank is. What do I have to add to three to get to 10? So you've had a go at it. Now let's see if we can do this together. So over here, I have three of these, I guess you could say purple, these purple pinkish circles and I have 10 boxes. One, two, three, four, five, six, seven, eight, nine, ten. So one way to think about it is, how many more circles do I need to add to fill up all of the boxes? Well, let's just count that together. I need to add one, two, three, four, five, six, seven to fill up all 10 boxes. So three plus what is equal 10? Well, three plus one, two, three, four, five, six, seven. is equal to 10. Let's do one more of these. So now I have six plus blank is equal to 10. So again, try to pause the video and see if you can figure out what the blank is. What do I need to add to six to get to 10? Let's do it together. So we now have one, two, three, four, five, six circles. We have 10 boxes here. One, two, three, four, five, six, seven, eight, nine, ten. So we just have to think about how many more circles do we need to fill up all the boxes to get to 10 because we already have six filled in. Well, we need one, two, three, four to get to 10. So let's just fill that in. Six plus four is equal to 10, or we could say even that four plus six is equal to 10, either way.