There are 27 4's in the number 28.
The same as the number of zeros in 10000, that is, 4.
21 5s
Rubidium has one 5s electron.
About 10000
3s has a principle quantum number of n=3 5s has a principle quantum number of n=5
The letter number combination of 5S indicates that your Browning sweet sixteen was produced in the year 1965.
10000+
1 of them.
7
16.
20