Your friend has written a program to check whether or not a number $\large n$ is prime. It is very simple and works by checking if $\large n$ is divisible by each number from 2 all the way to $\Large n-1$. When you see this, you curse your friend and tell him he's wasting time. What is the biggest number $\Large m$ that your friend needs to check before he can determine that any number $\large n$ is prime?

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