base 28 is a positional numeral system with twenty-eight as its base. It uses 28 different digits for representing numbers. The digits for base 28 could be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, and r.
quinary (base 5)
Quinary (base-5 or pental) is a numeral system with five as the base. A possible origination of a quinary system is that there are five fingers on either hand.