You do the math

Meaning

A dismissive way of telling someone the answer is obvious if they just look at the evidence. It is often used when someone is acting dense about a clear situation.

Sassy, impatient

Used in a sentence

• If he is never home and spends all his money on hobbies then you do the math.
• The project failed because nobody followed the instructions so you do the math.
• I have been working ten hour days every single week and I am still broke so you do the math.