Logic behind Justified P/S, P/B, P/E

Do any of you have shorthand ways to remember the formulas for Justified P/S, P/B, P/E? I’m having trouble recalling them but if you have some logic that I can simply derive in my head and come up with the formulas, it’d be tremendously helpful.

Also, if you have any logical tricks to get to their Forward looking counterparts, that’d be great too.