I (1) 26 30 (2) 9 8 16

Two (1) parallelograms (2) 15.

3.540 720 (1) = (number of sides-2) *180 (2) the sum of internal angles of a regular polygon of 260.

Four. Classification (addition principle): 50-minute stamps and 80-minute stamps, 160-minute stamps, 100-minute stamps and 130-minute stamps, 2 10-minute stamps and 180-minute stamps and four stamps.