Milikan oil drop experiment, were there really drops that picked up only one electron? There are representations like this:

The oil droplets can always absorb a multiple of the electrons, ultimately the simplest ratio is relevant. But such representations have even measuring points of nq with n=1 at the very bottom, were there really drops which have taken up only one electron?
 A: Below is a paragraph from Millikan's original 1913 paper which you can find online here https://journals.aps.org/pr/abstract/10.1103/PhysRev.2.109
It summarizes the results from the 58 drops that he included in the report including number of elementary charges on the drops observed which ranged from 1 to 136. So it looks like the answer to your question is yes, there are really drops which have only one extra electron.

Table XX. contains a complete summary of the results obtained on
all of the 58 different drops upon which complete series of observations
like the above were made during a period of 6o consecutive days. It will
be seen from this table that these observations represent a 3o-fold variation in $l/a$ (from .016, drop No. 1, to .444, drop No. 58), a 17-fold variation
in $p$ (from 4.46 cm. , drop No. 56, to 76.27 cm. , drop No. 10), a 12-fold
variation in $a$ (from $4.69 \times 10^{-5}$ cm. , drop No. 28, to $58.65 \times 10^{-5}$ cm. ,
drop No. 1) and a variation in the number of free electrons carried by
the drop from 1 on drop No. 28 to 136 on drop No. 56. The time of fall
of drop No. 28 was also tested when it was completely discharged, as
have been the times of many other drops which carried most of the time
but one electron.

