Sal adds 3-digit numbers by adding ones, tens, and hundreds.
Want to join the conversation?
- Knowing that is does not matter what order you add what number do you recommend to put on top the bigger or smaller one?(1 vote)
- Personally, I prefer to put the largest number on top, but that's just because it makes it easier to line up the other number so to match the place values correctly.
Like Sal does in this video:
- [Voiceover] So I have the number 163 and that is the same as, I have a one in the 100s place, so that's one hundred. Plus six 10s Plus three ones, three in the ones place. Do that in the color blue which I have for the ones place. And I've drawn that out here where I actually draw 163 squares. And you see it as one 100, six 10s. One, two, three, four, five, six 10s. And three ones. So this number right over here, 163, is the same thing as 100 plus six 10s plus three ones. And if you wanna think about what it looks like, this is 163 things. You see the 100, you see the six 10s. And you see the three ones. Now I now wanna add the number 324 to 163. So 324 is, if we look at the 100s place, it's 300s. It's two 10s, Three 100s plus two 10s, And four ones, so plus four ones. And we see that right over here drawn out, or I guess all the boxes. So 324 boxes, this is 324 boxes. You have three 100s, one two three 100s, Two 10s, one two 10s, And four ones. And so this number 324 is three 100s, two 10s, and four ones. And if you wanna think about how many boxes it is, it's that many, and you see them. They are grouped into three groups of 100, that's the 300s, two groups of 10, that's the two 10s, and then four ones. So now let's add them together. So let's first look at the ones place. So the ones place you're gonna have three ones plus four ones, well that's gonna be, let me do this in blue. That's going to be seven ones. Three ones plus four ones, that is seven ones. A seven in the ones place is seven ones. And we see that right over here. Three ones plus four ones, that's seven ones. Now I have six 10s and two 10s, well if I add them together I'm gonna have eight 10s. If I have six 10s and two 10s, the six and this two they're in the 10s place. So this represents six 10s, this represents two 10s. Six 10s plus two 10s is eight 10s. And we also see it here, six 10s plus two 10s is eight 10s. And finally we have one 100 plus another three 100s. So that's going to be four 100s. And you see them right over here, one, two, three, four. Four hundreds, let me circle all of these. 100 plus 300 is 400. So 163 plus 324 is 487. Four 100s, eight 10s, and seven ones.