Calculator XS by Naoto Fukasawa

Following on from the watches last week, here's another useful piece of modern-day design by Naoto Fukasawa - the Calculator XS.

The XS presumably stands for 'extra small', with this number cruncher just credit card-sized, but still packing in all the digits, an LCD and a solar panel, the latter two protected by a polycarbonate covering.

Lots of colours to choose from, all with a price of £17.50.

TwentyTwentyOne website