Let \( G \) be a cyclic group of order 12. The number of subgroups of a cyclic group is equal to the number of divisors of the order of the group.
The divisors of 12 are: 1, 2, 3, 4, 6, and 12.
Thus, the number of subgroups of a cyclic group of order 12 is the number of divisors of 12, which is 6.