The one I was referring to (and apparently others, though they 'solved' it) didn't know about modulo. Which would certainly make it harder, though it's ridiculously fundamental. They worked for about 20 minutes writing out something to do with a 101-element array and decimal arithmetic to initialize it (without using ceil / floor to compare, thus mimicking a mod function) before they admitted they were stuck.

This applicant was a graduate of some fairly high ranked university, though I don't know which one. They can come from anywhere.