What is the size of the largest subset S^{\prime} of S=\{2^{x} 3^{y} 5^{z}: 0 \leq x, y, z \leq 4\} such that there are no distinct elements p, q \in S^{\prime} with p \mid q.
What is the size of the largest subset S^{\prime} of S=\{2^{x} 3^{y} 5^{z}: 0 \leq x, y, z \leq 4\} such that there are no distinct elements p, q \in S^{\prime} with p \mid q.