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# Adding 3-digit numbers

CCSS.Math:

## Video transcript

we have three different addition problems right over here what I want you to do so that you get the hang of things is to pause the video and try them on your own but as you do them I want you to really keep in mind and think about what the carrying actually means so I assume you've tried it on your own I'll try to work them through I'll work through them with you so we have 9 plus 6 9 ones plus 6 ones well 9 plus 6 is 15 well we could write the 5 in the ones place and then we can carry the 1 but what did we just do what does this one represent well we put it in the tens place 1 10 represents 10 so all we said is that 9 plus 6 is equal to 10 plus 5 is equal to 1 10 plus 5 which is equal to 15 now in the tens place we have 1 plus 0 plus 9 which is 10 and so we can write 0 and carry the 1 1 plus 0 plus 9 is 10 now what does that really mean well this is 1 10 plus 0 tens plus 9 tens which is 10 tens 10 tens is a hundred or another way to think about a hundred it's 100 and 0 tens so that's all that carrying represents so now we have a 1 plus a 7 plus a 9 that is going to be 17 now we have to remind ourselves this is in the hundreds place so this is actually 100 plus 700 plus 900 or 1700 or 1700 and of course we still have this 5 here and we are done now let's try to tackle this one now the reason why I wrote it that way is to make sure that we remind ourselves to align the proper places under the appropriate places so this one we can rewrite as 300 and I'm doing that same green color we could rewrite this as 373 plus we want to write the ones place under the ones place in the tens place under the tens place so that we're adding the appropriate place values so 3 plus 8 is 11 the one in the ones place the 1 in the tens place 10 plus 1 is 11 1 plus 7 is 8 8 plus 8 is 16 this is actually 16 10 so let me just write down the 16 what is 16 tens well that's 160 so this six is the 60 and then I have a hundred one plus three is four but these are actually hundreds so it's four hundred so we get four hundred and sixty-one now finally 9 plus 3 is 12 two ones and one 10 12 is the same thing as 10 plus 2 now in the tens place 1 plus 4 plus 9 is 14 so we write the 4 carry the 1 but remind ourselves this is actually 10 plus 40 plus 90 which is a hundred and forty which is the same thing as 40 plus a hundred and then one plus one plus two is four but this is in the hundreds place so this is actually 100 plus 100 plus 200 or 400 and we're done