diff --git a/05-isPrime/index.js b/05-isPrime/index.js
index ec9c4ac..6e7afa2 100644
--- a/05-isPrime/index.js
+++ b/05-isPrime/index.js
@@ -1,4 +1,11 @@
 export function isPrime(value) {
   // implementar logica aqui
-  
+  if (isNaN(value) || !isFinite(value) || value % 1 || value < 2)
+    return false;
+  if (value % 2 == 0) 
+    return (value == 2);
+  for (let i = 3; i <= Math.sqrt(value); i += 2) {
+    if (value % i == 0) return false;
+  }
+  return true;
 }
\ No newline at end of file