oK so this question is actually based about me and my friends going to the pub and they have a gambling scheme where it is 1 pound to stake.

You must choose 5 different numbers from numbers 1-40

you must match 3 numbers that are drawn to win the prize of 1200 pound + your stake is added to the pot.

How many different number combinations are there and is it worth betting on every different combination.

I worked out 666 different combinations based on -

numbers 12345 12346 12347 etc... there are 36 combinations.
23456 23457 23458 etc... 35 combinations

so 36+35+34+33 must cover every number. so if we stake 666 pound we guarantee a win of 1200+666 which is 1866. unless someone else wins also. which is unlikely. we also win several times with each win, eg 123 is covered 35 times so we get 35/36 of the winnings.

tell me if im wrong but its a no lose situation?

Thanks - Spud