The supplier receives his orders from the five buyers once every 2 weeks, once every 6 weeks, once every 8 weeks, once every 4 weeks, and once every 3 weeks. The number of occasions where all the five buyers place the order on the same day is : The LCM of the 5-time frames during which the 5 buyers place their orders : Hence the LCM is : (2,6,8,4,3).=24‌weeks. Once every 24 weeks, all five of them place the order simultaneously. A year has 53 weeks in total : Hence all five of them place the orders after 24 weeks, 48 weeks.