Question 181
Carla wrote on the blackboard the integer numbers from $1$ to $21$. Diana wants to erase some of them in such a way that by multiplying the remaining numbers the result is a perfect square.
a) Shows that Diana must necessarily erase the numbers $11$, $13$, $17$ and $19$ to achieve her goal.
b) What is the smallest number of numbers that Diana should erase to achieve her goal?
a) Shows that Diana must necessarily erase the numbers $11$, $13$, $17$ and $19$ to achieve her goal.
b) What is the smallest number of numbers that Diana should erase to achieve her goal?