The school has set up three extracurricular activity groups: reading, music and calligraphy, and each student can participate in at most two groups (unnecessary). at least

Two interest groups have three kinds of participation, namely reading and music, reading and calligraphy.

The opposite of the same situation for at least six students is that the above three situations happen to have five students in each group, so * * * * has 3×5= 15 students.

If there is one more student, there must be six students in the same situation, so the final answer is 15+ 1= 16.