An ice cream shop has 10 flavors of ice cream and customers are allowed to choose any combination of flavors, as long as at least one flavor is chosen and each flavor is chosen only once. If the order of the flavors does not matter, in how many ways can a customer create their ice cream?

so there are 10 flavors, so, there are 1024 combination(2^10),

in 1024 ways, there is combination which has no flavors option(i.e choosing none)

Since it was mentioned that atleast one flavor need to be choosen , we substract that combination

1024-1

why is it 2^10?