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# Subtracting 1, 10, or 100

CCSS Math: 3.NBT.A

## Video transcript

- [Voiceover] I have here the number 324, which we can view as, since I have a three in the hundreds place, we could say this is three hundreds, I have a two in the tens place, so we could say, plus two tens, and then I have a four in the ones place, so I can say, plus four ones, and if you want to think about what that looks like, you could look at all these blocks here. Three groups of 100, three groups of 100, one, two, three, two groups of 10, two groups of 10, I have two groups of 10 right over here in yellow, four ones, I have four ones here, so this is 324 blocks. So now let's get some practice subtracting from 324, and the first thing I want to subtract from 324 is, let's subtract a 10. So, I want to subtract a 10 here. So a 10 is one 10 and zero ones. Let me do that in the blue color. Zero ones. So, I'm not subtracting any hundreds, I AM subtracting one 10, you see it right over there, so minus one 10, and I'm not subtracting any ones, so what is that going to get me? What is that going to get me? Well, my hundreds don't change. I'm not subtracting any hundreds, so I still have three hundreds, so I could write that over here, I still have three hundreds, I had two tens, I'm taking one of them away, so now I have two minus one is, two minus one is one 10. I had two tens, now I take away one 10, I should just call that a ten instead of a tens, I take away one 10, and now I'm going to have plus one 10, if I had two, I take away one, I'm now going to have one, and I had four ones, and I'm not taking any ones away, so I still have four ones, four ones minus zero ones, four ones. So I'm left with 314, three hundreds, plus one 10, plus four ones, and if you look at it over here, what did we do? We had 324, and then we take away one of the tens, so we took away one of the tens, and we are left with three hundred, one 10, and four ones, or 314. That was interesting. Now let's subtract 100 from 324 instead of a 10, so, let's now subtract, let's now subtract 100, so that's one hundred, so I'm now gonna subtract one hundred, and zero tens, and zero ones, so let's subtract that now. What's that going to be? Well, I had three hundreds, I take one of them away, now I'm going to have two hundreds. I had two tens, I take away no tens, I still have two tens. I had four ones, I take away zero ones, I'm still going to have four ones. If you look at it over here, what's that going to be? Let me write an equal sign. I had three hundreds, I take away 100, I'm going to have two hundreds. I had two tens, I'm not taking away any tens, so I still have two tens, and I had four ones, and I'm not taking away any ones, so I still have four ones, and if you think about it in this picture here, what did I just do? Well, I took away one group of 100. I took away one group of 100, so I could take away that group of 100 right over there, and what am I left with? I'm left with two hundreds, two tens, that's the two tens there, and four ones. Two hundreds, let me write it this way, two hundreds, two tens, four ones, or 224.