Mark M. answered 09/24/19
Retired college math professor. Extensive tutoring experience.
60 = 1, 61 = 6, 62 = 36, 63 = 216, ...
104 ÷ 36 = 2R32
32÷6 = 5R2
So, 104 in base 10 is the same as 2(36) + 5(6) + 2 = 2(62) + 5(61) + 2(60) = 252 in base 6.