The Abacus iPhone Case embodies a playful balance of analog versus digital technology when you fit it to your iPhone 4 or 4s. Simple mathematics can be done without counting your fingers or poking your touchscreen calculator, but rather by sliding little markers across tiny tracks to carry out addition, subtraction and some slightly more complicated arithmetic.
Joaquin Baldwin's smartphone protector is made from white nylon plastic and forms a frame around the entire outside edge of your handset. Across the back, it features nine horizontal lines that are crossed with a single vertical one to the right side, and small Apple icons are the beads that run along them. You can slide these back and forth when the Abacus iPhone Case is on your mobile, but detach it and you can spin them too.