These are actually 6 houses and not 4. From west the 2nd shows number 7, the 3rd the 3 (which looks a little odd to me.) For the others I did not find a number visible from the street.
The postboxes are all together. It could as well be that the building has only one number, which is just not shown, and the numbers above mean something else.

via StreetComplete 62.1