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2 Digit Subtraction

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hi parents and students at this is the video for two-digit subtraction you will see me do three strategies that I've taught in class the algorithm which is what we learned how to do parents Ashley the number one before we get started there are few chance that I've taught the students and when I mean chance this is just ways tricks to help them know where to start and for instance where do we start friends like I'm so vehicle we start at 1 but I mean the ones place value with subtraction we have A3 Saenz if there's more on top no need to stop at what I mean is going to be if I'm starting in my ones more on top meaning the bigger number is the four would be the bigger number no needs to stop that's not the but that would be for instance if it was 4-7 no need to stop you and just subtract the next thing we have is it the number is the same zero is our game so let's say we had this and we started in our one's the number is the same zero is our game lastly you'll see this problem here the same genus if there's more on the floor which I tell before there's more hair the seven is greater than the four we've got to go next door to the tens place and get 10 more and once I take the 8 and it becomes seven and we move a ten stick because it's not a t anymore it's 70 we move a 10-second to the ones place value and it is 10 + 4 is 4 14 - 7 and we've been working on your fluency 14-7 is 7 7 - 5 to strategy now the next one is called build it take it and so here we've got 84-57 equals and we're going to build base 10 they look like this and these are 10-6 and these are one walks you'll notice that 10 10 ones would equal if I win them up in a row one of these 10 6 built the big number which is 84 and we take 57 away 8 + 6 1 2 3 4 5 six seven eight and there's four one so then I do dots for once and now I have to take this away I'm done with the 84 we start in the ones so what number is a my17 do I have 712 take away I don't so I have to come to my tens and bring it over and that would be like taking this 10 stick and breaking it it would break into 10 ones so here's what we would have you'll notice I've got these lined up and five in a row now we can take 7 away 2 3 4 5 6 7 7 is correct now we have to go to 10 you'll notice that I've already taken one away but that was for regrouping which is what we did when we moved our 10 stick over to our ones by breaking it now I have to take 5 more away count with me 1 2 3 4 5 what am I left with 210 6 so you'll notice we got the same answer last but not least strategy the number one and the way this works is we do 84-57 since we are subtracting Which Way friends are we going to jump forwards or backwards we're going to jump backwards because I'm number line on the number line are number is going to be smaller for our answer our answer will be smaller I'm going to start with the fake number can I put my big number here and jump backwards no we've got to put it down here so I've got 84 now I'm going to have to jump backwards 57 times where can I expand or break it apart to where it's 50 + 7 that the expanded form of 50 so we would have 5 10 jumps and 7-1 jumps so 510 dumps 1/2 for thought and I'm going to do - 10 - 10 - 10 - 10 + - 10 + friends they know that we count and last but not least we have 1 you'll notice I sound when I hit one two three four five six seven and those are all going to be minus one 84 - 10 the only digit that will change will be the one that's in the tens place so 80 - -10 which would be like 8-1 would be 4 6454 44 + 34 now he's got to count by 1 3332 31 30 29-28 and last but not least we land on 27 you'll notice I solve this three different ways and I want your you got to be able to use all different methods so they can check their work thank you

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2 Digit Subtraction

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