diff --git a/04-fibonacci/index.js b/04-fibonacci/index.js
index 37c64cc..1cd2471 100644
--- a/04-fibonacci/index.js
+++ b/04-fibonacci/index.js
@@ -1,4 +1,9 @@
-export function fibonacci(value) {
+export function fibonacci(value, memo) {
   // implementar logica aqui
-  
-}
\ No newline at end of file
+  memo = memo || {}
+
+  if (memo[value]) return memo[value]
+  if (value <= 1) return value
+
+  return (memo[value] = fibonacci(value - 1, memo) + fibonacci(value - 2, memo))
+}