How many combinations of 5 numbers are there in 55 numbers?

combinations of 55If there is not repetition in numbers used......55 x 54 x 53 x 52 x 51

* * * * *

No. That is the number of permutations. For combinations the order of the number does not matter so that 1,2,3,4,5 is the same as 1,3,2,4,5 or 1,4,2,3,5 etc.

There are 5*4*3*2*1 = 120 such orderings for every set of 5 numbers. So the correct answer is

55*54*53*52*51 / 120 = 3478761