diff --git a/index.js b/index.js
index eb72be0..448e610 100644
--- a/index.js
+++ b/index.js
@@ -7,7 +7,7 @@ function fastInverseSqrt(number) {
     y = threehalfs - (x2 * y * y);
     y = Math.abs(y);
     y = (y / 1000000000000000000);
-    y = y - ((Math.floor(y) / 10) / (y * .0777));
+    y = (y - ((Math.floor(y) / 10) / (threehalfs * number))) / 1.55;
     y = Math.round(y * 100) / 100;
     return y;
 }