A, B, C start running at the same time and at the same point in the same direction in a circular stadium.  A completes a round in 252 seconds, B in 308 seconds and C in 198 seconds.  After what time will they meet again at the starting point?

46 minutes 12 seconds

Required time = LCM of 252, 308, 198 = 2772 seconds or 46 minutes 12 seconds