Puzzle 19 - Homework Scores |

In a Matrix Algebra class
there were n tests. The absent-minded professor put all the
scores into an n × n matrix M in some strange
order. John wants to find his total score and he knows that his scores
are on the main diagonal. By paying one dollar to the professor, John
can find the total sum of the entries in a square submatrix of M
of John’s choice. What is the smallest sum of money that John
has to pay to find out his total score? |