The number 60 has 12 factors: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60. If we divide each by 60 we get: 1/60, 1/30, 1/20, 1/15, 1/12, 1/10, 1/6, 1/5, 1/4, 1/3, 1/2, 1. The given sequence contains 5 of these and asks for a further seven to complete the set of 12. The missing numbers in order are: 1, 1/3, 1/5, 1/10, 1/15, 1/20, 1/30,