CalcPad is a portable smart notepad that calculates answers based on what is typed in.
It allows you to type in math expressions, assign variables, define functions, convert units, add units together and much more. There is no enter button, it automatically evaluates everything you type as it's typed. You can go back and edit, add, or delete anything you want at any time, just like a notepad, and all the calculations will update accordingly.
CalcPad was designed to take full advantage of the computer screen, keyboard, and mouse. In the past, many people tried to simulate calculators as closely as possible. They would even purposely add limitations to make it behave more like a regular calculator. For example, with many physical calculators, if you are typing in expressions and make a mistake, you had to start all over again. On a PC there is no reason for this, but people would add that behavior as if it was a feature. Because of this, the author created CalcPad.