If you want to know exactly what the _Mix Color_ mode "_Color_" does, here is a mathematical explanation:

The color A gets scaled by 1 - _Factor_. Then a combination of color B's _Hue_ and _Saturation_ with color A's _Value_ will be scaled by the _Factor_. The results of these scalings/multiplications are added together to give the final result.

So this setup:

[![mix color node][1]][1]

can be recreated mathematically with this node setup (well, actually you can do it with less nodes, I just extended it a bit to show the components a bit better):

[![recreated color mode][2]][2]


  [1]: https://i.sstatic.net/KnWUED0G.png
  [2]: https://i.sstatic.net/IY9s1lMW.png