Adding 10 or 100
Sal adds 1, 10, or 100 to a number.
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- I sometimes get the answer wrong.what can I do?(12 votes)
- If you are have trouble with any topic on Khan Academy, you should watch the video again, then after that, if you are still having trouble understanding, ask your teacher, your parents, friends, siblings, or other family. I am sure they would love to help.(13 votes)
- Is there a faster way to add without using the squares?(8 votes)
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- 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.