Remember that for a function to have an inverse, the function must be 1-to-1. The two functions must also be symmetrical about the line y=x, which is apparent in the second graph.
Im assuming you are trying to convert scientific notation to a number. In that case 1.18 x 10 to the third power would be 1,180 and 9.1 x 10 to the -6 would be .0000091.
