Skill 6H Subtraction: Use Addition to Check Adding to check is a technique used to make sure the answer to a subtraction problem is correct. Here, when telling your student to "add to check," he/she should know to make an addition problem by taking the answer to the subtraction problem and adding it to a number in the subtraction problem. For example, using the subtraction problem 8  2 = 6, we would then "add to check" using 6 + 2 = 8. Answer the subtraction problem, 

