123. What number does not change when raised to a power? What number retains its absolute value when raised to any positive integer power?
123. The only common roots of all equations of the type $x^{n}=x(n=1,2,3 \ldots)$ are 1 and 0. Any complex number of the form $\cos \alpha+i \sin \alpha$ (and therefore especially the numbers: $-1, i$ and $-i$) always retains its absolute value when raised to any power.