Video: Adding Three Numbers up to 999

298 + 57 + 502 = _

02:05

Video Transcript

298 plus 57 plus 502 equals what?

In order to add these three values, we’ll want to stack them up vertically. I’m going to start with 502 because it’s the largest value. And I want that value to go on top. Because we’re doing only addition, we can stack these values in any order that we want to. After that, we line up 298 and then 57.

Now let’s check that all of our place values have been lined up correctly, units with the units, all of the tens places lined up, and all of the hundreds places are lined up. Now that we’ve checked that, we’re ready to start adding.

Starting all the way on the right, we add two plus eight plus seven. Two plus eight equals 10, and 10 plus seven equals 17. 17 is seven units and one ten. Write down the seven; carry the one. Now we add the tens place: one plus zero plus nine plus five. Altogether, that’s 15 tens. We write down our five tens and carry over our one into the hundreds place. 10 tens is equal to 100. In the hundreds, one plus five plus two equals eight. Eight hundreds, five tens, and seven ones equals 857.

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