When we add, we combine two or more numbers to come up with one aswer called the sum.
This module have problems involving the addition of single digit numbers. All sums are less than 18.
When we add three digit numbers, we add first the 2 numbers then add its sum to the third number.
We can add numbers vertically and horizontally.
In addition sentences, If you change the grouping of the addends in an addition sentence, the sums stay the same.