There are eighteen 5's in 90 !
90
21 5s
In the Rb atom, the electron configuration is [Kr]5s^1. This means there is 1 electron in the 5s sublevel of the Rb atom.
24
10
20
75
7
i think there are 18 digit 5s.
There are eleven 5s in 55. This is determined by dividing 55 by 5, which equals 11.
66 of them.
Exactly 33 of them