A promise, discounted
So far money has walked forwards in time, growing as it goes. Present value walks it backwards: if someone promises you dollars in years, what is that promise worth today? Undo the growth — divide by the factor instead of multiplying: — read aloud: PV equals FV over one-plus-r to the t.
The idea underneath is worth keeping for life: a dollar promised for next year is worth LESS than a dollar in your hand, because the dollar in hand could be growing already. Dividing by is exactly compound interest run in reverse — same factor, opposite direction. And a free answer check: if your value-today comes out BIGGER than the promise, you multiplied when you should have divided.
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