diff --git a/Maths/NumberOfDigits.js b/Maths/NumberOfDigits.js
index 8a3e2b3c6a..7207ce9b94 100644
--- a/Maths/NumberOfDigits.js
+++ b/Maths/NumberOfDigits.js
@@ -7,7 +7,12 @@
  *
  */
 
-const numberOfDigit = (n) => Math.abs(n).toString().length
+const numberOfDigit = (n) => {
+  if (typeof n !== 'number' || !Number.isFinite(n)) {
+    throw new TypeError('Input must be a finite number')
+  }
+  return Math.abs(Math.trunc(n)).toString().length
+}
 
 /**
  * Returns the number of digits of a given integer.
@@ -17,7 +22,20 @@ const numberOfDigit = (n) => Math.abs(n).toString().length
  * @see https://math.stackexchange.com/questions/2145480/how-does-the-logarithm-returns-the-number-of-digits-of-a-number
  * @author dev-madhurendra
  */
-const numberOfDigitsUsingLog = (n) =>
-  n === 0 ? 1 : Math.floor(Math.log10(Math.abs(n))) + 1
+const numberOfDigitsUsingLog = (n) => {
+  if (typeof n !== 'number' || !Number.isFinite(n)) {
+    throw new TypeError('Input must be a finite number')
+  }
+  const intVal = Math.trunc(n)
+  if (intVal === 0) return 1
+  const abs = Math.abs(intVal)
+  let digits = Math.floor(Math.log10(abs)) + 1
+  if (Math.pow(10, digits - 1) > abs) {
+    digits--
+  } else if (Math.pow(10, digits) <= abs) {
+    digits++
+  }
+  return digits
+}
 
 export { numberOfDigit, numberOfDigitsUsingLog }
diff --git a/Maths/test/NumberOfDigits.test.js b/Maths/test/NumberOfDigits.test.js
index e3495eb9ea..6a78b3d30b 100644
--- a/Maths/test/NumberOfDigits.test.js
+++ b/Maths/test/NumberOfDigits.test.js
@@ -13,11 +13,22 @@ describe('NumberOfDigits', () => {
     [0, 1],
     [123423232, 9],
     [-123423232, 9],
-    [9999, 4]
+    [9999, 4],
+    [999999999999999, 15],
+    [1000000000000000, 16],
+    [1000000000000001, 16]
   ])(
     'should return the correct number of digits in an integer',
     (value, expected) => {
       expect(numberOfDigitsUsingLog(value)).toBe(expected)
+      expect(numberOfDigit(value)).toBe(expected)
     }
   )
+
+  it('should throw TypeError for invalid inputs', () => {
+    expect(() => numberOfDigit('123')).toThrow(TypeError)
+    expect(() => numberOfDigit(NaN)).toThrow(TypeError)
+    expect(() => numberOfDigitsUsingLog('123')).toThrow(TypeError)
+    expect(() => numberOfDigitsUsingLog(NaN)).toThrow(TypeError)
+  })
 })