Partial Sums

When we first learn how to add, we are just taught how to do it. Most of the time, the teacher did not take the time to explain why we are doing so or even how. With the partial sums method, you are personally learning how to add. It shows you how to add the non-shortcut way. It also shows you what is actually happening through out the problem.

Let's say you want to add 456+231. You would first add the 100's. 400+200=600. Then you would add the 10's. 50+30=80. Then, last but certainly not least, you would add the ones. 6+1=7. Finally you would add all of the partial sums together. 600+80+7=687.

You should do this method from left to right and add the columns.

In this example, it is actually showing you step by step what is happening in the problem: