Rational fractions will terminate only if the denominator’s prime factors are the base’s factors. So for example, 1/2 = 0.5 and 1/5 = 0.2, but 1/3 = 0.333… and

Rational fractions will terminate only if the denominator’s prime factors are the base’s factors. So for example, 1/2 = 0.5 and 1/5 = 0.2, but 1/3 = 0.333… and 1/7 = 0.142857…. 1/4 = 0.25 works because the prime factors of 4 are 2 and 2… but 1/6 fails because 6 is infected by 3. Now, base 12 has 2 prime factors (2 and 3) so it much any better than 10 really. But may I introduce base 30 (235)? Or perhaps base 210 will strike your fancy?