ahosey: Actually, 3 is not the smallest coefficient.
The number of decimal digits required to represent the positive number x is floor(log10(x)) + 1. The largest unsigned integer which is N bytes long is 256^N (actually it's 256^N-1, but 256^N always has the same number of digits as 256^N-1, since 256^N is never a power of 10).
It follows that the number of digits required to represent an unsigned integer of N bytes is floor(N * log10(256)) + 1. So the actual smallest factor is more like 2.408, but don't forget the addition of one.
Open question: Do we need a more "open" MathWorld? Perhaps a Wiki-like system?