This calculator has some very peculiar display features, including a slash between digits that can be used to display fractions without loosing a digit. The overall keyboard layout is quite nice. Also nice is the back-space key. The OP1 and OP2 keys provide a form of semi-programmability. For instance, when you want to add the number "13/2" to a series of other numbers, simply type + 1 3 ÷ 2 OP1. Now, when you type 5 OP1, the result will be the outcome of "5 + 13/2". The power source is 1x CR2032 battery The calculator is assembled in Italy The calculator will be packed carefully.