Imagine my excitement at being told, at the age of 13, that I was allowed to use a calculator in Maths lessons. “Outrageous!” cried my parents. But they kindly bought me one, nonetheless, so that I could do those exponential sums, work out cosines, and perform probability and combination calculations without resorting to writing on reams of graph paper. And probably getting it wrong.

Look, it still works. It always sits on my desk. Solar powered. Hasn't died once. It's slightly filthy, yes, but I could give it a clean and it would be as good as new. Has anyone else still got a trusty piece of electronic equipment that they've not only managed to hang onto, but still works after 21 years of use? I'm slightly in awe of this thing, now.

EDIT – I'm a bit worried that actually this was my second Casio calculator. 's comment below has been something of a memory jogger. In which case it's not quite as old as I thought. But it's still pretty old, so the sentiment remains, er, similar.