One from my company's past, a desk top calculator from 1966. Biro for size comparison!
We're loaning this one & many others to the National Museum of Computing at Bletchley.
I'll post a few more photos of the insides of the machine as and when I remember. Really
interesting how things have moved on in the last 50 years. The only real difference between
this and today's pocket calculators (other than size and power requirements) is that it has
16 digits compared to 8 for most pocket calculators.