Arithmetic Grade Four

Lesson Three: Addition Review

The answer you get when adding numbers is called the sum. When you add 4 and 5 you get a sum of 9. Put another way, the sum of 2 and 4 is 6. Study these examples:
5 + 1 = 6 The sum of five and one is six.
3 + 2 = 5 The sum of three and two is five.
3 + 4 = 7 The sum of three and four is seven.
1 + 8 = 9 The sum of one and eight is nine.

There are many ways to produce the same sum.

You can add up two numbers and produce the same sum in many ways. Study these examples:
SUM OF 6: 1+5, 2+4, 3+3, 4+2, 5+1
SUM OF 9: 1+8, 2+7, 3+6, 4+5, 5+4, 6+3, 7+2, 8+1

On certain tests you might be given a problem like this:

Do all the following problems produce the same sum? (true or false)

  • 5+3=
  • 4+4=
  • 2+6=
    • ANSWER: _______
    The answer to this example is true. Often when answering true or false questions you can just enter t for true and f for false. The quiz on the next page allows you to enter a t for true or f for false.

    Continue to next page of lesson