Can you solve this bit of a maths problem for me? it's from a show called Stargate SG1.

39 symbols on a gate, 7 symbols dial an address in any sequence. How many addresses can be dialled overall? :)

39! / (39-7)! = 39! / 32! = 77519922480

I am fan of the Stargate SG1 series.
I think the number of chevrons available are 38.
One chevron can be used at one time.

But not all combinations result in a valid stagate location.

39!/32!

(if you allow symbols to be used only once in a permutation. Otherwise 7^39)