(1) Among the positive integers less than 20, select three different numbers such that their sum is divisible by 3. The number of different ways to do this is $\qquad$.
(1) 327 Hint: $\mathrm{C}_{6}^{3}+\mathrm{C}_{6}^{3}+\mathrm{C}_{7}^{3}+6 \times 6 \times 7=327$.