Let's say I have a set of five elements for people to choose from. They are allowed to choose multiple elements.

`['a', 'b', 'c', 'd', 'e']`

Is there a way to store a single value so that from that value I can determine which elements they chose? One option I thought of was to store as a binary string. So if they chose `a` and `b` I would store it as `11000`. If someone chose `a`, `b`, and `e`, it would be stored as `11001`. I'm wondering if there was a different method. I couldn't think of the appropriate terms to search online. Thanks.