IBPS Clerk Prelims Model Paper 18

Let the numbers be 5x, and 6x and 7x. Then, their L.C.M. = 18x. So, 18x = 3600 or x = 20
∴ The numbers are (5 × 20), (6 × 20) and (7 × 20)
Hence, required H.C.F. = 20