Is it really necessary to print a ticket?

[Idbl]

I've registered online, and the page said that I needed to print the
emailed ticket. However, I don't have a printer. Is it enough to copy
down the number that is printed along the side of the bar code? It
strikes me as superfluous to require one to bring printed copies of
tickets when the event is free to attend.

Anyone involved in organizing have any information about this?

Thanks :)