There are 27 4's in the number 28.
The same as the number of zeros in 10000, that is, 4.
21 5s
100
3s has a principle quantum number of n=3 5s has a principle quantum number of n=5
10000+
1 of them.
The letter number combination of 5S indicates that your Browning sweet sixteen was produced in the year 1965.
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.
7
20
24