There are 100 3's in 300 or 1... depending upon how you look at it.
There are: 300/3 = 100
how many 3s gointoo 33
28 3s
103
The first three is 3000 and the second three is worth 300.
The are two electrons in the 3s orbital of magnesium (Mg.)
How many 3s are in 15
37.6666667
9
16
4
0
10