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## 2nd grade

### Course: 2nd grade > Unit 4

Lesson 1: Visually adding within 1,000# Adding 10 or 100

Sal adds 1, 10, or 100 to a number.

## Want to join the conversation?

- I sometimes get the answer wrong.what can I do?(25 votes)
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- Is there a faster way to add without using the squares?(19 votes)
- You can regroup numbers, use your fingers or just practice adding small numbers mentally and eventually you will be able to do bigger numbers without even writing.(13 votes)

## Video transcript

- So I have the number 235,
and we can think of that as 2 hundreds, we have a
2 in the hundreds place so 2 hundreds, 3 tens, we
have a 3 in the tens place, so 3 tens, and 5 ones, we
have a 5 in the ones place. And over here I've actually drawn it out with that many boxes, this is 235 boxes. So you have 2 groups of a hundred boxes, so this is 2 hundreds,
then we have 3 tens, 1,2,3. And then we have 5 ones. Now let's try some
interesting things here. So what happens if I were to add 10 here. Well adding 10, we're just adding 1 ten. We're just adding 1 ten. So if we add 1 ten,
what's going to happen? Well, over here I need to add one more 10, I've got to add this 10. So what's it going to look like? Well that, the next 10 is
going to look like this. Let me see if I can draw it pretty fast. So we have one, two, three, four, five, six, seven, eight, nine, and ten. One, two, three, four, five, six, seven, eight, nine, ten. So I just added a ten. So what does that leave us with? Well if I had 3, if i had 3
tens, and I have 1 more ten now, now I'm going to have 4 tens,
now I'm going to have 4 tens. I'm gonna do that in that yellow color. So now I'm going to have 4 tens. I'm still going to have 5 ones, 5 ones, I'm still gonna have 5 ones,
I'm not adding any ones there. So I'm still going to have 5 ones, and I'm still going to have 2 hundreds, I'm not adding any hundreds there, so I'm still going to have
2 hundreds, 2 hundreds. So now it's going to be 2 hundreds, plus 4 tens, plus 5 ones. 2 hundreds plus 4 tens plus 5 ones. Well what's that going to be? Well, 2 hundreds, plus 4 tens, plus 5 ones: 245. Let's do one more. Instead of adding a ten,
let's add a hundred. So let's do that, let me see if I can clear all this stuff out, so... So instead of adding 10 lets add 100 here, so I'm going to add, so plus, let's add 1 hundred, 1, I'll actually do it in yellow and in blue. So I'm adding 1 hundred,
0 tens, and 0 ones. So essentially just adding 1 hundred. So this is going to be
equal to, so plus 1 hundred. So plus 1 hundred, so
what's that going to get me? Let me draw it out here,
let me copy and paste. I have 2 hundreds before but
now I'm going to add 1 hundred. So let me just copy that,
and let me paste it. So now, how many hundreds do I have? How many hundreds do I have now? Well now i have one, two, three hundreds. I have 3 hundreds. So over here, I had 2 hundreds, I'm adding one more
hundred right over here so now I have 3 hundreds. Over here I could say that
now I have 3, 3 hundreds. Now, are the number of
tens, have they changed? No, I had 3 tens before, and
I'm not adding tens this time so I'm still going to
have 3 tens, and I had 5 ones before and I'm
not adding any more ones so I still have 5 ones. So I have 335, which is the same thing as 3 hundreds plus 3 tens, plus 3 tens, plus 5 ones, plus 5 ones.