INMO 1987 Problem 3

Let $T$ be the set of all triplets $(a,b,c)$ of integers such that $1 \leq a < b < c \leq 6$ For each triplet $(a,b,c)$ in $T$ , take number $a\cdot b \cdot c$ . Add all these numbers corresponding to all the triplets in $T$ . Prove that the answer is divisible by 7.