I am an idiot
The university enforces a rather cunning policy where you can only use their certified calculators in exams. And you can only buy their certified calculators in their shop. Sly, eh? So I bought one for myself the other day,as I will be needing it.A week later and it wasn't working. I tried leaving it in the sun, and that had little effect, even though it was part solar. Frustrated I tried some cell batteries I happened to have, but the calculator needs special batteries which are obtainable from god knows where. Rather than searching for these, I decided to go to the shop and buy a new one- they are only ten pounds after all.
I got it home just now, and tried to turn it on. It didn't work. I stared in frustration for a second. Then I noticed something. Unlike a lot of calculators, the clear button was not the on button. I pressed the on button. It switched on. I went to the other calculator and pressed the on button. It also switched on.
Sigh... what a waste of ten pounds.....