Balance mixed operations quiz online. This is an interactive online math test to check kid’s skills on addition and subtraction. The idea in this case is to find missing numbers that would otherwise make an equation balanced for example __ + 2 = 6 – 3. The missing number in this case is one. If it is replaced in the equation, both sides will have equal outcomes. There is more in the worksheets section. Print out and get more practice. This exercise will help teachers and parents supplement their kid’s regular course. This activity is for for 2nd, 3rd, 4th, 5th grades.