To me it definitely seems to be in the puzzler category based on those descriptions. The trick is realizing it's "just" asking you to solve the well known formula for radius to circumference, 2*pi*r=c, for c=6 would give r≈1 while you can ignore the rest of the information worded to trick you into thinking it's a complicated problem which would require a fancy solution. Of course if you're not dealing with geometry every day of your adult life it's more likely it leads to seeing what your general thought process is, such as "I'll fall back to Fermi Estimation to get a ballpark going".