docs(sprint-1): add concise answers for currency conversion interpretation

Author: Tarawally

Sprint-1/3-mandatory-interpret/3-to-pounds.js

@@ -25,3 +25,26 @@ console.log(`£${pounds}.${pence}`);
 
 // To begin, we can start with
 // 1. const penceString = "399p": initialises a string variable with the value "399p"
+
+// 2. const penceStringWithoutTrailingP = penceString.substring(0, penceString.length - 1);
+// Removes trailing "p" from "399p" to get "399"
+// substring(0, 3) extracts characters from index 0 to 2
+// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/substring
+
+// 3. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+// Ensures string has at least 3 characters by adding leading zeros
+// "399" stays "399", but "9" would become "009" (for 9p = £0.09)
+// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/padStart
+
+// 4. const pounds = paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2);
+// Extracts all except last 2 characters for pounds
+// "399" → substring(0, 1) → "3" (£3)
+
+// 5. const pence = paddedPenceNumberString.substring(paddedPenceNumberString.length - 2).padEnd(2, "0");
+// Extracts last 2 characters for pence and pads to 2 digits
+// "399" → substring(1) → "99", then padEnd(2, "0") → "99"
+// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/padEnd
+
+// 6. console.log(`£${pounds}.${pence}`);
+// Formats and displays result using template literal: "£3.99"
+// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals