It's a matter of ratios
so E6 is the simplest set still in use, which means that parts with a 20% tolerance just about overlap
100, 150, 220, 330, 470, 680
Then E12, for 10% tolerance parts
100, 120, 150, 180, 220, 270, ....
Then E24 for 5% parts
100, 110, 120, 130, 150, 160, 180, ....
Then E48 for 2% parts and so on up to E192
100, 101, 102, 104, 105, 106, 107, 109, 110, ...