Actually, FordPrefect, it isn't the fact that it's less than 2 that causes the problem.

Consider base sqrt(5), which is greater than 2. (sqrt(5) ~ 2.236). Take decimal 280, which is 2010100_{sqrt(5)}. But the usual conversion routines will give 10000000.1001..._{sqrt(5)}, since sqrt(5)^{7} is 279.51, which is closer to 280 than 2*sqrt(5)^{6}, or 250.

Same for base sqrt(10), which in some ways is easier to work in, and is greater than 3. 322 decimal is "obviously" 30202_{sqrt(10)}, but it's also 100012.12..._{sqrt(10)}, by similar reasonings.

I'm thinking it may also have to do with the way the base^{0} place works. Ponder: the equations 10-1=(b-1) (where b-1 is the *digit* for one less than the base b) works for all integer bases, but does *not* work for irrational bases. The problem is that we're using integer multiples of integer powers of the base, and when the base isn't an integer that isn't so well-behaved anymore.