Elcalc is opensource calculator, there is simple design with beautiful interfaces. This application support in any platform like Windows, Mac and Linux.
My suggestion is add more features for this application. There is can be add Scientific feature to calculate the a formula and add Programmer for calculate IT programmer and also add Statistic feature for the Accountant.
Before add the features :
After add the features, combined in a picture in below :
In below shown in different features :
Adding more features in elcalc application is very useful because this app can be operation for Scientist for calculate the formula, IT programmer to calculate biner numbering, and else the Accountant for statistic.