Video Gallery

Subtracting by adding up on a number line

Go to Video Gallery Added Sep 30, 2015 •

Copy this URL:
Embed code:	<iframe class="edlio-embed-player" type="text/html" width="640" height="360" src="//lvm.lgusd.org/apps/embed/?v=90186" frameborder="0" allowfullscreen></iframe> Change dimensions

Go HD

Show Transcript

let's look at how to use the subtracting by adding up strategy on a number line but first let strategy works turn examples with some much smaller numbers and will be working with  let's look at the example of 8-5 if we were to subtract 8 - 5 are answer of course would be three now one way of looking at that on a number line is starting with when counting back 5  so we go to 726-2524 and finally two three there we took away our 1 2 3 4 5 another way of looking at that problem on a number line putting 8 and 5 on the number line and then counting in between them to see what that difference is  in that way we would start at 8 count back to 7 count back to 6 and count back to 5 now in this case you have our answer being what number we landed on like it was in the first problem and this case her answer would be shown by the difference how far we had to jump 1 2 three now if we look at that same number line once again thinking about 5 and 8 we can see that it's actually possible to count the same numbers but in the opposite direction starting at 5 and counting up to 8 adding one to get to six another to get to 7 and adding Arthur to get to a so there we see that the difference Works in two directions either way there apart so since we know that difference is the same weather we start with 8 and count back to 5 or start with V and count up to 8 that shows that we can add lower number to get up to the higher number take a look at how to use that to solve a much larger problem cuz I think we know we're not going to be working on solve 8 - 5 let's take a look at safe 4126 - 2000 548 first of all just like yesterday I need to turn this into an adding on equation showing that we can start the smaller number  add on the difference which we don't know yet but we'll figure out and then end up at the larger number the difference between are of adding up with equations and adding up with a number line is a course the fact that we were using the number line so first of all after we've turned our subtraction turn into an addition equation adding on equation to draw a number line to show our work  once again we're going to start with lower number but now show that below our number line remember the number line the numbers below our Landing spots the numbers we write on top are the differences how apart word jumping between two different numbers just like with our strategy yesterday we're going to add up to the next 10 so if I look at where I'm 2548 I know end up with something that's as 2500 but I have to go up to the next tens place right now I'm in the 40s I'm going up to 50  48 and 50 are the two numbers we need to find the difference between so I can drama jump and I can count on from 40 250 where I can think I have eight ones right now I'm trying to make another 10 we can use our tens fact to know that eight plus two more would equal that 10 so we bad up to the next 10 a nice easy stopping point now us add up to the next 100 after that number here we see that where we have 2,000 150 that the next Hunter going up would be 2600  so you can now look how many tens we have and how many 10 think about how many tens are going to have to add to make that other hundred  we have 50 which is 5 tens we know that 100 is what 10 tens so we need 5 more times which is 50 once again are 10 facts really help us with this strategy now we're going to add on to next thousand  I see by looking at are starting number here on this step 2600 that are next thousand would be 3000 please stop by 1 but then of course we have no hundreds tens or once cuz thousands are only made of thousands  once again we can use tens facts to help we're trying to make another thousand we're beginning with 600 knowing that a thousand is made of ten hundreds we need for more parrots  now we can have from 3000 up to  the higher number 4126 if we look at the number word starting with and we were ending up a few of these should be pretty easy for us to figure out if we start is there an end up with 6 I'm going to be adding 6 if we start with 0 tens and end up with 20 we must be adding 20 so two tens if we start with 0 hundreds an end up with 100 you must be adding one if we start with three thousands and end up with for thousands we must be adding one of those now we have all of chances of our difference and we need to add them together to figure out total difference we have a few different choices of how to add those we can add those horizontally just the way they're written and then write our total here or we could write them vertically stacked  1001 r26 450 and 2 and noticed that I kept all my digits lined up my turns my tens my hundreds and my bausen digit are all lined up either way we can add these together and we would get  8 what's 2 + 6 making we would have 7/10 there's 50 and 20 which makes 70 chance we see there's 400 there's 401 so we have five and we only have $1,000 so just 1000 so we can see our total difference is 1570 so then we want to write that into both power equations poison girls I hope that helps you with subtracting by adding up on a number line

Video Gallery

Subtracting by adding up on a number line

Popular Videos