4 1.2 0.36 0.108 what are the rules of these figures?

4 1.2 0.36 0.108 what are the rules of these figures?

The latter is 0.3 of the former, for example, 4 * 0.3 = 1.21.2 * 0.3 = 0.360.36 * 0.3 = 0.108