Addition of three numbers math quiz. In this activity children will learn how to add three one digit numbers. For example, 2 + 3 + 6 = 11. There are gap-fill and multiple choice questions exercises in this quiz. Children can learn on their own while online with this activity. By learning how to add three numbers, children prepare themselves for more challenging exercises ahead. This activity is for children in 1st, 2nd and 3rd grades. It is recommended for teachers and parents who wish to get their kids to do more homework practice.