Question

Here is my Lua code for taking user input, and checking if the number entered is prime. My issue is that the program thinks that any even number is not prime, and any odd number is.

 print("Enter a number.")
 local number = io.read("*n")

 function prime(n)
 for i = 2, n^(1/2) do
   if (n % i) == 0 then
     return false
   end
   return true
 end
 end

 if prime(number) == true then
   print("Your number is prime!")
 end

 if prime(number) == false then
   print("Your number is not prime!")
 end

Answer 1

Move return true out of the loop.

Hence:

function prime(n)
    for i = 2, n^(1/2) do
        if (n % i) == 0 then
            return false
        end
    end
    return true
end