Complex Calculator Precision 18 is a complex number calculator and works with complex numbers, but also can be used as a real number calculator, that is a scientific calculator. The calculator has backward compatibility with College Scientific Calculator series and Scientific Calculator Precision 54. Any formula which works in College Scientific Calculator will work in this calculator. For that some buttons are duplicated. Button Mod stands for modulus and works on the same way as abs button. Button mod stands for modulo. Button Log stands for principal value of complex Log and is duplicated by button ln. Button log(z) works as Log(z)/ln(10) for complex z and as decimal logarithm for real z, although in Complex Analysis log denotes multi-valued function log(z)=Log(z) 2πni.