The greatest possible number of club members is the greatest
common factor of 12, 18, 36 since all of these quantities of books have to be distributed
evenly:
The factors of 12 are 1, 2, 3, 4, 6, 12
The factors of 18 are 1, 2, 3, 6, 9, 18
The factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18, 36.
The greatest common factor for this three numbers is 6.
As a result, the greatest possible number of club members is 6.
