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Lesson 24: More Complicated Addition
Very often there is a need to add more than two numbers. The procedure is the same, but it requires a bit more work. This lesson explains.
Don't forget to watch the embedded video clip for this lesson at the bottom of the page. Please be sure to read the embedded video information and disclaimer.
To add a list of numbers, just line them up on top of each other like you've been doing, being careful to line up each digit according to its proper place value. For example, if you're adding 123 + 45, the 2 should be on top of the 4, since both are in the tens place. If you don't line up the numbers properly, your answer will be completely wrong.
Take
a look at the problem at left. To add three numbers like this, we
must line them up properly. Only one number has a digit in the
thousands place, and so there are no other digits are in that column.
Always just remember to line up all the ones place digits properly on
the right, and everything else will be lined up correctly.
First we'll add the ones place, since we always start on the right with that column. 5 + 9 is 14. Now we have to add 8. Either do it in your head, or on a piece of scrap paper, and you'll get 22. Just like we've done before, the 2 in the ones place goes below the line, and we'll carry the 2 that represents 20 into the tens place. Now we'll add up all the digits in the tens place, including the 2 that we carried. We'll add 2 + 4 + 6 + 9 to get 21. Again, the 1 goes below the line, and the 2 gets carried into the hundreds place. We'll add the digits in the hundreds place to get 18, writing the 8 below the line, and carrying the 1. In the thousands place, all just add 1 + 1 to get 2, giving us a final answer of 2812.
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