Arithmetic Grade Four

Lesson Two: Addition Review


Two Column Addition

When adding numbers with two digits, you add the digits in the ones column together and the digits in the tens column together like this:

        
        34
       +41
       ---
        75

It's almost like you are doing two separate additions. For the ones column you do the problem 4 + 1 = 5 and for the tens column you do the problem 3 + 4 = 7.

Here's another example:

        
        17
       +32
       ---
        49

In this case you add 7 and 2 in the ones column to get 9. In the tens column you add 1 and 3 to get 4. These problems do not have to be arranged as shown in the examples. We can rearrange them like this and the answers remain the same:

        
   34 + 21 = 55

   17 + 32 = 49

If you like doing these problems one way better than the other, you can rewrite them on a piece of scratch paper when they are presented in the way you don't like doing them. So, if you are presented with:

        
   63 + 21 = 

You can rewrite it like this on a piece of scratch paper.

        
        63
       +21
       ---
        84

Either way the answer will still be the same.

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