[shcfslrp] Duodecimal denominators

Divisors of 12^2 = 144: 1 2 3 4 6 8 9 12 16 18 24 36 48 72 144, so denominators of fractions expressible in two digits in base 12. Compare with 1 2 4 5 10 20 25 50 100 which are the two-digit decimal denominators.

Previous base-12 fractions.