do the math!
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!