Question 560066

Number of combinations having only one object = 1C1 = 1  i.e A

because every combination must include object A. 


number of combinations having two objects = 5C1 = 5

as we have to choose another 1 out of other 5 objects, A has been chosen already.


similarly, 
number of combinations having three objects = 5C2 = 10



total number of possible combinations = 1 +5C1 + 5C2 + 5C3 +5C4 +5C5



if any doubt, feel free to ask....