Thread: What is this notation

Hello all, I hope I'm posting in the right place. I am doing some laser flash lamp calculations and ran across this: tube life =[Ein/Eex]-8.5
I understand that I must devide Ein by Eex but what is the notation out side the brackets. I have never seen that before. Thanks in advance.

do you mean the notation inside the brakets? if not then all the notation outside the brackets means is that you must subtract 8.5 from the answer you get from the division.

Hello you Sinebar (only responding to his greeting).