Logging onto a laptop with a non-functional 'r' key

A friend of mine was given a Mac laptop (I don't have the model yet). Her logon password contains the letter 'r', but the letter 'r' on the keyboard is now non-functional. Is there a way to enter an 'r' using the mouse and a table of displayed characters ... maybe something which disabled users might use to type ... with which my friend can log on to her machine and change her password to one not containing an 'r' ?

Many thanks for any help with this.

Got a USB keyboard? It'd work.

Thanks

Thanks.
Perfect solution.
Now have the machine in hand, and more than one key is non-functional.
So an external keyboard is the answer.
Didn't think of it, but it's pretty obvious once you do!
Thanks again.