Before the luxury of pocket calculators, computers or even slide rules, if you needed to do some calculations in a hurry an option would have been to use an Arithmometer. They are relatively small mechanical devices that could be used to calculate using the four basic functions, and were quite popular up until the mid 20th century.
Taking an interest in these older devices, Diego Cueva created his own emulated version using an Arduino-compatible circuit, a large LCD and many extra buttons. It works well and shows an interesting window to calculating devices of the past, for example:
This is a fun project, and if you're mathematically-inclined and looking for a new project you can make your own using the details on Diego's project page. And for more, we're on twitter and Google+, so follow us for news and product updates as well.
If you're wanting to experiment with your own Arduino-compatible circuits, then you'll need a an ATmega328P MCUs with Arduino Uno bootloader:
This is the same Atmel AVR ATmega328P microcontroller used in the official Arduino Uno, as well as our Eleven, EtherTen, USBDroid, and other boards. Perfect for building your own Arduino-compatible project directly on a breadboard or on a custom PCB, or for replacing the MCU in an existing board. Comes with the Arduino Uno bootloader pre-installed. Better still, it even has a special label stuck on top with details of the pinout, so you don't even need to look up the datasheet when connecting it up in your project! For more information and to order, click here!