From c44d3024084452a38e10bcc5a1f5e15ea57e6c60 Mon Sep 17 00:00:00 2001
From: sarthakgupta1907-cell <sarthakgupta1907@gmail.com>
Date: Sat, 7 Nov 2026 10:41:20 +0530
Subject: [PATCH] feat: add neon number algorithm

---
 Maths/NeonNumber.js           | 25 +++++++++++++++++++
 Maths/test/NeonNumber.test.js | 47 +++++++++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+)
 create mode 100644 Maths/NeonNumber.js
 create mode 100644 Maths/test/NeonNumber.test.js

diff --git a/Maths/NeonNumber.js b/Maths/NeonNumber.js
new file mode 100644
index 0000000000..94a16a7704
--- /dev/null
+++ b/Maths/NeonNumber.js
@@ -0,0 +1,25 @@
+/**
+ * @function isNeonNumber
+ * @description A neon number is a number where the sum of digits of
+ *   its square equals the number itself.
+ *   For example, 9: 9² = 81, 8+1 = 9.
+ * @param {number} n - A non-negative integer
+ * @returns {boolean} - True if n is a neon number, false otherwise
+ * @see https://en.wikipedia.org/wiki/Neon_number
+ * @example isNeonNumber(9) => true
+ * @example isNeonNumber(1) => true
+ * @example isNeonNumber(0) => true
+ * @example isNeonNumber(2) => false
+ */
+const isNeonNumber = (n) => {
+  if (!Number.isInteger(n) || n < 0) {
+    throw new TypeError('Input must be a non-negative integer')
+  }
+  const square = n * n
+  const digitSum = String(square)
+    .split('')
+    .reduce((sum, d) => sum + Number(d), 0)
+  return digitSum === n
+}
+
+export { isNeonNumber }
diff --git a/Maths/test/NeonNumber.test.js b/Maths/test/NeonNumber.test.js
new file mode 100644
index 0000000000..1f627f4101
--- /dev/null
+++ b/Maths/test/NeonNumber.test.js
@@ -0,0 +1,47 @@
+import { isNeonNumber } from '../NeonNumber.js'
+
+describe('isNeonNumber', () => {
+  test('0 is a neon number (0²=0, 0=0)', () => {
+    expect(isNeonNumber(0)).toBe(true)
+  })
+
+  test('1 is a neon number (1²=1, 1=1)', () => {
+    expect(isNeonNumber(1)).toBe(true)
+  })
+
+  test('9 is a neon number (9²=81, 8+1=9)', () => {
+    expect(isNeonNumber(9)).toBe(true)
+  })
+
+  test('2 is NOT a neon number (2²=4, 4≠2)', () => {
+    expect(isNeonNumber(2)).toBe(false)
+  })
+
+  test('3 is NOT a neon number (3²=9, 9≠3)', () => {
+    expect(isNeonNumber(3)).toBe(false)
+  })
+
+  test('5 is NOT a neon number (5²=25, 2+5=7≠5)', () => {
+    expect(isNeonNumber(5)).toBe(false)
+  })
+
+  test('10 is NOT a neon number (10²=100, 1+0+0=1≠10)', () => {
+    expect(isNeonNumber(10)).toBe(false)
+  })
+
+  test('8 is NOT a neon number (8²=64, 6+4=10≠8)', () => {
+    expect(isNeonNumber(8)).toBe(false)
+  })
+
+  test('throws TypeError for negative input', () => {
+    expect(() => isNeonNumber(-9)).toThrow(TypeError)
+  })
+
+  test('throws TypeError for float input', () => {
+    expect(() => isNeonNumber(9.5)).toThrow(TypeError)
+  })
+
+  test('throws TypeError for string input', () => {
+    expect(() => isNeonNumber('9')).toThrow(TypeError)
+  })
+})