Update BMI calculation to round using toFixed

Author: Pretty Taruvinga

Sprint-2/3-mandatory-implement/1-bmi.js

@@ -15,5 +15,7 @@
 // It should return their Body Mass Index to 1 decimal place
 
 function calculateBMI(weight, height) {
-    // return the BMI of someone based off their weight and height
-}
+  // return the BMI of someone based off their weight and height
+  const bmi = weight / (height * height);
+  return Number(bmi.toFixed(1));
+}