The number of triangles whose vertices are at the vertices of a regular octagon but none of whose sides is a side of the octagon is

If the sides $AB, BC$ and $CA$ of a triangle $ABC$ have $3, 5$ and $6$ interior points respectively,then the total number of triangles that can be constructed using these points as vertices is equal to ....... .

The sum of all absolute values of the differences of the numbers $1, 2, 3, \ldots, n$,taken two at a time,i.e.,$\sum \limits_{1 \leq j < i \leq n} |i-j|$ equals:

There are $3$ girls in a class of $10$ students. The number of different ways in which they can be seated in a row such that no two of the three girls are together is

Out of $10$ points in a plane,$6$ are in a straight line. The number of triangles formed by joining these points is:

If the number of diagonals of a regular polygon is $35$,then the number of sides of the polygon is