Some students are standing in a square. Counting from any of the eight directions, Victor is the fifth. How many students are there?
Hint
It is not 100.
Answer
Since Victor is the fifth counting from any direction, there are 5+5-1=9 students on each row and each column, and there are 9*9=81 students.
The students stand like this: V is where Victor stands:
S S S S S S S S S
S S S S S S S S S
S S S S S S S S S
S S S S S S S S S
S S S S V S S S S
S S S S S S S S S
S S S S S S S S S
S S S S S S S S S
S S S S S S S S S