In the reading room of a library, there are 23 reading spots. Each reading spot consists of a round table with 9 chairs placed around it. There are some readers such that in each occupied reading spot there are different numbers of readers?

What Its Saying Is, For Each Table (23) With People On, The Amount Of People At The Table Are Different.
Table 1- 1 Person (Total=1) Table 2- 2 People (3) Table 3-3 People (6) Table 4-4 People (10) Table 5- 5 People (15) Table 6- 6 People (21) Table 7- 7 People (28) Table 8- 8 People (36)
By The 8th Table All The Spaces Have Been Filled So, 23-8=15 Tables Unoccupied.