Event Viewer - Get help, support, and tutorials for Windows products—Windows 10, Windows 8.1, Windows 7, and Windows 10 Mobile.
Numi App - Numi is a beautiful text calculator for Mac.
Soulver - Soulver is a software application that functions as a calculator that allows you type a continuous stream of information rather than having to input data into multiple cells.
Qalculate! - Qalculate! is a multiplatform multi-purpose desktop calculator.
SymCalc - Symbolic Calculator - Math toolbox for iOS. Advanced calculator features with a tape-like history, not requiring internet...
GeoGebra Scientific Calculator - Free online scientific calculator from GeoGebra: perform calculations with fractions, statistics and exponential functions, logarithms, trigonometry and much more!