Why is a scale of 1: 1,000,000 considered smaller than 1: 100,000?

A scale with a ratio of 1: 1,000,000 is considered smaller than a scale with a ratio of 1: 100,000, since there is 10 km of the real surface in 1 centimeter of the first scale, and 1 kilometer in the second scale, 1 centimeter.
Therefore, the second scale is more detailed, since a map with such a scale displays a surface 10 times smaller.

For example, if the object is 2 cm on the first scale, then its real length will be 2 * 10 = 20 km.

And in the second case:
2 * 1 = 2 km.