Decimal: Each wheel has digits 0-9. When a wheel reaches 9 and increments, it rolls over to 0 and the next wheel increments.
Binary: Each wheel has only 0 and 1. When a wheel is at 1 and increments, it becomes 0 and the next wheel increments.
Hexadecimal: Each wheel has 0-9 and A-F (where A=10, B=11, C=12, D=13, E=14, F=15). After F, it rolls to 0.
Watch how the different bases "carry" at different rates - binary carries most frequently, hexadecimal least frequently!