From 22cc7412c327145a1ffd573ea7e73bb4b76fd2e5 Mon Sep 17 00:00:00 2001
From: sarthakgupta1907-cell <sarthakgupta1907@gmail.com>
Date: Sat, 7 Nov 2026 01:58:29 +0530
Subject: [PATCH] feat: add palindrome number algorithm

---
 Maths/PalindromeNumber.js           | 23 +++++++++++++++
 Maths/test/PalindromeNumber.test.js | 43 +++++++++++++++++++++++++++++
 2 files changed, 66 insertions(+)
 create mode 100644 Maths/PalindromeNumber.js
 create mode 100644 Maths/test/PalindromeNumber.test.js

diff --git a/Maths/PalindromeNumber.js b/Maths/PalindromeNumber.js
new file mode 100644
index 0000000000..2b7d5214c4
--- /dev/null
+++ b/Maths/PalindromeNumber.js
@@ -0,0 +1,23 @@
+/**
+ * @function isPalindromeNumber
+ * @description Checks whether a given integer is a palindrome.
+ *   A palindrome number reads the same forwards and backwards.
+ *   Negative numbers are not palindromes.
+ * @param {number} n - An integer
+ * @returns {boolean} - True if n is a palindrome number, false otherwise
+ * @see https://en.wikipedia.org/wiki/Palindromic_number
+ * @example isPalindromeNumber(121) => true
+ * @example isPalindromeNumber(1221) => true
+ * @example isPalindromeNumber(-121) => false
+ * @example isPalindromeNumber(123) => false
+ */
+const isPalindromeNumber = (n) => {
+  if (!Number.isInteger(n)) {
+    throw new TypeError('Input must be an integer')
+  }
+  if (n < 0) return false
+  const str = String(n)
+  return str === str.split('').reverse().join('')
+}
+
+export { isPalindromeNumber }
diff --git a/Maths/test/PalindromeNumber.test.js b/Maths/test/PalindromeNumber.test.js
new file mode 100644
index 0000000000..5ac4e902fa
--- /dev/null
+++ b/Maths/test/PalindromeNumber.test.js
@@ -0,0 +1,43 @@
+import { isPalindromeNumber } from '../PalindromeNumber.js'
+
+describe('isPalindromeNumber', () => {
+  test('121 is a palindrome number', () => {
+    expect(isPalindromeNumber(121)).toBe(true)
+  })
+
+  test('1221 is a palindrome number', () => {
+    expect(isPalindromeNumber(1221)).toBe(true)
+  })
+
+  test('12321 is a palindrome number', () => {
+    expect(isPalindromeNumber(12321)).toBe(true)
+  })
+
+  test('0 is a palindrome number', () => {
+    expect(isPalindromeNumber(0)).toBe(true)
+  })
+
+  test('1 is a palindrome number', () => {
+    expect(isPalindromeNumber(1)).toBe(true)
+  })
+
+  test('123 is NOT a palindrome number', () => {
+    expect(isPalindromeNumber(123)).toBe(false)
+  })
+
+  test('10 is NOT a palindrome number', () => {
+    expect(isPalindromeNumber(10)).toBe(false)
+  })
+
+  test('negative numbers are NOT palindromes', () => {
+    expect(isPalindromeNumber(-121)).toBe(false)
+  })
+
+  test('throws TypeError for float input', () => {
+    expect(() => isPalindromeNumber(1.5)).toThrow(TypeError)
+  })
+
+  test('throws TypeError for string input', () => {
+    expect(() => isPalindromeNumber('121')).toThrow(TypeError)
+  })
+})