A scientific calculator provides calculations within a limit of 1 to 240 significant digits. Formulas are written in natural notation and are built of operators, constants and variables, and are limited to a length of 250 characters. The number of arguments is limited to 73. The syntax of the formula is verified and all error is interpreted. The compilation of the formula is followed by the optimization of the calculus.According to run mode chosen, the calculation may be followed by a report with a list of arguments and all intermediate results in chronological order. The user can choose a System Keyboard (48 standard functions) as well as the Private one (with 48 customizable keys). Every "private" button can be titled and linked to any formula entered by the operator at any moment and for permanent using. Besides, jExacter has a simple and direct mode of calculation called CASH REGISTER that enables a continuous addition of numbers, products, percents and divisions (precision limited to 25 digits) with the control of the syntax of arguments and operations.