Originally Posted by noglider

@yankeefan, my wife is the most environmentally conscious person, and the reused key is fine with her. It's just that the bar code may or may not work, and of course, the missing digit was super lame. It took our two minds to figure it out. She noticed the fact that a digit was missing, and it was my idea to try all possible values, rather than give up. I'm not sure she'll have time to try Citibike today, but I'll report whether the key works.

And here's something odd. She has the thing everyone calls a key, which goes on a key ring. I have a credit-card sized card, which I have to keep in my wallet. How do they decide which to send? I don't remember stating a preference.