How many 5 number random combinations of numbers are there between 1-40?

Assuming without repeats:

40C5 = 40!/(40-5)!5!

= 40x39x38x37x36x35x34x...x2x1/(35x34x...x2x1)x(5x4x3x2x1)

= (5x4x2)x(3x13)x38x37x36/5x4x3x2x1

= 13x38x37x36

= 658008