Jon teaches ... at an elementary school where class sizes are always at least 100 students and at most 200.
One day Jon decides that he wants to arrange the students in their desks in a rectangular grid with no gaps.
Unfortunately for Jon he discovers that doing so could only result in one straight line of desks.
What is the largest number of students that Jon could have in his class?
The number is 199 because 199 is the largest prime number less than 200.
If one straight line is the only possible resultant, then the number has to be
prime. A prime number has no factors other than 1 and itself. A non-prime
number could be factored, thus having the possibility of more than a single
row of desks.
.