int i, j, count =0;
for (i=2; i<=100; i++)
for (j=1; j<=i; j++)
if (i % j == 0)
if (count == 2)
Console.WriteLine("This is a prime number" + i);
count = 0;
1. You should have the second loop condition like
Actually you need to check whether the number is divisible with 1, 2.... upto the number you are comparing with (that is i).
2. Count should be 0 every time, but you are making it 0 when it is prime, inside the if condition.
So, 2, 3 are prime, and when 4 comes it does not make count 0, hence stops.