Chance are you didn't listen when your math teacher said you'd need to know all those formulas and functions later in life, yet here you are, looking for math software. Not a problem, because WisePair's WiseCalc has your number. It's a free scientific calculating engine that can handle some pretty sophisticated high-level stuff, such as evaluating functions and matrix expressions, performing unit conversions and row operations, and much more. It has hundreds of built-in functions and unit conversions and nearly every useful formula and constant known to science. Users can define their own, too. In fact, if you have a mathematical or scientific formula or calculation that WiseCalc can't handle, there's a high probability you're no stranger to white lab coats and research grants and have needs that free mathware can't meet.
WiseCalc will be familiar to many in its previous iteration, PC Calc. It's been expanded, updated, and upgraded. Fairly small at 1.3MB, it installs at C (the speed of light) because it's all straight math, with very little of the complex coding needed to handle the biological interface (that would be you). WiseCalc is easy for humans to use, though: just a toolbar with a few extra buttons, such as Radian and Decimal, and an Object Browser sidebar containing three tabs, constants, Functions, and Units; as clean an elegant as an equation.
If you need powerful math tools and scientific data at your cursor-tip, WiseCalc adds up. If you need more than it does, see your research director.