Arithmetic Grade Four

Lesson Twenty-three: Whole Number Addition

Study and try to answer this problem: 


      68
      +7
     ----
When we add the two numbers in the ones column we get 15. From this we know that the answer to 68 + 7 is going to be more than 70. In fact the answer is 75. We can count starting at 68 until we have added seven like this: 

  68: 69, 70, 71, 72, 73, 74, 75
       1   2   3   4   5   6   7
This will get us the answer. In the next lesson we will learn about a better way of doing this kind of problem.

Here's another problem for you: 

     77
     +4
    ----
Using the counting method we count four times starting at 77: 

   77: 78, 79, 80, 81
        1   2   3   4

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