Number of sub-sequences in a given sequence

Question

If I am given a sequence X = {x1,x2,....xm}, then I will have (2^m) subsequences. Can anyone please explain how can I arrive at this formula intuitivel

Answer 1

The value x_i can either be in the subsequence, or not. This is just like a bit. There are 2^m combinations for turning on / turning off the m numbers in the sequence.