log of complex numbers.

(1+2 i)/(log(10))

=0.43429448190325182765112891891660508229439700580366656611... +
0.86858896380650365530225783783321016458879401160733313222... i

This looks hard but I will give it a try.

$\text{Let }x=\log\left(e^{(1+2i)}\right)\\ 10^x= e^{1+2i}\\ 10^x=e\times (e^i)^2$

$e^{i\pi}+1=0\\ (e^i)^\pi + 1=0\\ (e^i)^\pi=-1\\ e^i=(-1)^{\frac{1}{\pi}}$

$10^x=e\times (-1)^{\frac{2}{\pi}}\\ 10^x = e\times (1)^{\frac{1}{\pi}}\\ 10^x = e\\ x = \log e$