the boys of a school can be arranged in 12,15 and 18 equal rows and also into a solid a square.what is the leat number of boys that the school can have ? (hint find the lcm)

Answer 1

The hint really gives you the answer.
12 = 3*2*2
15 = 3*5
18=3*3*2
so least common multiple is 3*3*5*2*2 = 180

12 rows of 15
15 rows of 12
10 rows of 18

Answer 2

900