Work through a word problems that involve 3-digit addition.
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- Why does Khan Academy take so long to load?(4 votes)
- why do we use number lines instead of normal adding?(0 votes)
- At this stage, learn and use the method rather than questioning it to understand the reason for the methods. These methods are the result of hundreds of years of experience. Once you learn to use the method, experience it, and understand it as a result, you may question why. Proceed step by step. It is good to question, but sometimes trying to question without learning and understanding will just be a waste of time.(3 votes)
- [Instructor] We're told, the table gives the amounts of materials Aya recycled. So we have the different materials here, and then it gives the various amounts. How many kilograms of paper and aluminum did Aya recycle? So pause this video and see if you can figure this out. Okay, so we're thinking about paper and aluminum, so paper is right over here. She recycled 277 kilograms of paper. And aluminum is right over here. She recycled 134 kilograms of aluminum. And so we want the combination, or the sum, of paper and aluminum, so it's going to be 277 kilograms plus 134 kilograms. So we really need to figure out what 277 plus 134 is, and in multiple videos, we have talked about how there's many different ways of approaching this. We could say, well let's just break up the 134. We could start at, actually let me do this on a number line. That sometimes is a fun thing to do. So if we were to just say, this is our number line, and we're going to start at 277 right over there. So first, we could add 100, because we have 100 right over there, so let's do that. If we add 100, so plus 100, where does it get us? Well if we add 100 here, we get to 377. So 300, I'll just write, 77. And then we could add three 10s, or 30. So then we're going to add 30. So let's add 30, so plus 30. What does that get us? So this is interesting. If you add 30 to 370, you would get to 400, and then we have another seven there, so that gets us to 407. So then we get to 407. And once again, this is just one way to try to think about it. And then, last but not least, we could add the four. So then you say, we're there right now, and then we add plus four, and seven plus four is 11, so 407 plus four is 411. So how many kilograms of paper and aluminum did Aya recycle? Would be 411 kilograms. Kilo, kilograms, and we're done.