Do the Math is a phrase that is used to encourage someone to use their math skills to solve a problem. The crossword solutions for this phrase are CALCULATE (9 letters), ADD (3 letters), and SUM (3 letters). CALCULATE is an action that involves using mathematical processes to determine a numerical answer. ADD is an action that involves combining two or more numbers together to get a total. SUM is another word for ADD, and it is also used to describe the result of adding two or more numbers together.