How to Backspace in Calculator?

So this is a pretty silly question, but I can't seem to figure it out on my own or with Google.

When using the built-in calculator, everything works as expected, except I can't delete/backspace. For example, if I want to enter 112 but accidentally type 113, I'd expect to hit delete/backspace to delete the last typed digit, and then enter 2 instead. However, as far as I can tell this is not possible. You have to clear everything by hitting "C".

This is on a Mac Mini with the bluetooth wireless keyboard. Needless to say, the delete key (or fn+delete) works just fine everywhere else.

Am I just missing something obvious?

(Yosemite 10.10.4)