In a colony of 100 blocks of flats numbering 1 to 100, a school van stops at every sixth block while a school bus stops at every tenth block. On which stops will both of them stop if they start from the entrance of the colony?

First stop at which both van and bus stops = LCM of 6 and 10 = 30


Hence, the stops at which both of them stop = 30, 30 + 30 = 60 and 30 + 30 + 30 = 90


197