The number of parallelograms that can be formed from a set of four parallel lines intersecting another set of three parallel lines is

Everybody in a room shakes hands with everybody else. The total number of hand shakes is 66. The total number of persons in the room is

The number of triangles that are formed by choosing the vertices from a set of 12 points, seven of which lie on the same line is

The number of ways in which a team of eleven players can be selected from 22 players always including 2 of them and excluding 4 of them is

The number of 5-digit telephone numbers having atleast one of their digits repeated is