Commit 17cad3a

@@ -14,7 +14,11 @@ public class Number {
   }
 
   public static boolean isPrime(int n) {
-    return false;
+    if (n <= 1) return false;
+
+    for (int i = n - 1; i > 1; i--) if (isDivisibleBy(n, i)) return false;
+
+    return true;
   }
 
   public static boolean isDivisibleBy(int n, int denominator) {