how many options out of 8

[moti barski]

is this correct :
given 8 buttons, user can press 1 or 2 or...8

sum of
8 : 1
7 : 8
6 : 8*7*6*5*4*3
5 : 8*7*6*5*4
4 : 8*7*6*5
3 : 8 * 7 *6
2 : 8 *7
1 : 8

8842 ?