I wish more programs followed the design principles of Soulver. It does one particular thing very well, which is to act as a bridge between the features of a calculator and a spreadsheet. This solves a surprising number of the numerical exercises that I go through every day, both in the realm of finance (job) and electronics (hobby). By allowing you to save your sessions, you can encapsulate knowledge in a way thats more transparent than a spreadsheet, where the formulas must be examined cell by cell and cant be scanned holistically, as Soulver allows you to do. Can you replicate Soulver with Excel? Of course. But do you need to wait for Excel to load, utilize the memory it uses, etc.? Not for a great many problems. Soulver sits open on my desktop most of the time, and I tend to use it for scratch calculations, thought exercises, and rapid prototyping of numerical algorithms. Very useful, not expensive, and well designed.