Possible method:

-start at origin (0,0); after 1N,1E: at (1,1) ; 2S,2W: (-1,-1) ; 3N,3E: (2,2) ; 4S,4W: (-2,-2) ....

-calculate position (x,y) that Clarke Kent ends at

-distance = SQRT(x^2 + y^2)

Take 79 miles travelled: position = (-4,-4) after 72, so (-4,3) after 79.

So distance = SQRT[(-4)^2 + 3^2] = 5.

Looks promising...I'll try that tomorrow; you try too!...g'nite!