1st Calculator is a Business::Applications software developed by RomanLab Software. After our trial and test, the software was found to be official, secure and free. Here is the official description for 1st Calculator: Handy and useful expression calculator and unit converter with skins. Main features: fully customizable interface with skins; keyboard shortcuts; all arithmetic operations, more than 20 functions; editable lists of constants and unit conversions; recalling previously used expressions; five result formats with changeable precision; automatic clipboard copy/paste; minimizes to the system tray. you can download 1st Calculator 1.15 free now.