do the math
1. Literally, to do a bit of arithmetic calculation. Primarily heard in US, South Africa. Well, let's just do the math to see if you have enough in your savings account to afford a new car.
2. To figure out or put together information for oneself. Primarily heard in US, South Africa. Do the math—can't you see that he's just using you to get ahead in the company?
do the math!
work it out for yourself (used to suggest that the conclusion to be drawn about something is obvious). North American informal Math is the American abbreviation of mathematics . When the phrase is used in British English, it is usually as do the maths .
2004 BBC News: Business I was faced with the choice of either topping up by using paid holiday or a vast reduction in earnings and a financial struggle when I least need it. You do the maths!