Question 174108
No. Because some numbers are factors of 3 AND 5 which would make them be counted twice. Take this for example up to 20:
3:3,6,9,12,15,18
5:5,10,15,20
If you used the students way it would equal 10 different numbers. But if you have noticed, 15 has both so right there, there are only 9 DIFFERENT numbers