A group of $630$ children is arranged in rows for a group photograph session. Each row contains three fewer children than the row in front of it. What numbers of rows is not possible?
Let the no. of students in front row be x.
So, the no. of students in next rows be x–3,x−6,x–9 ... so on
If n is the no. of rows then no. of students (n=3)
Similarly for n=4
Hence n ≠ 6
Hence,Option (4)6 is the correct choice.