My understanding is that I can find out whether a function is injective, surjective / bijective by plotting the graph and noticing how many intersections there at a given point. I'm working through a few examples but I am stuck on this one.

f(x) = 10^6 - 2^-x

It does not seem practical to plot this curve (I'm not using a graphing calculator).

Do I just use a particularly large scale and plot points as normal?