There are 100 3's in 300 or 1... depending upon how you look at it.
28 3s
103
The first three is 3000 and the second three is worth 300.
To find out how many 3s go into 140, divide 140 by 3. This gives you approximately 46.67. Since we're looking for whole 3s, you can fit 46 complete 3s into 140.
37.6666667
16
9
4
2,560
3000/3 = 1000
203
There are: 21/3 = 7