diff --git a/other/happy_number.py b/other/happy_number.py
new file mode 100644
index 00000000..a4a1b8b0
--- /dev/null
+++ b/other/happy_number.py
@@ -0,0 +1,62 @@
+# Mengecek apakah angka adalah sebuah happy number atau sad number
+# https://en.wikipedia.org/wiki/Happy_number
+def sum_digit(number):
+    value_digit = 0
+    while number > 0:
+        digit = number % 10
+        value_digit += digit * digit
+        number = number // 10
+    return value_digit
+
+
+def happy_or_sad(number) -> str:
+    """
+    Happy number adalah sebuah angka yang dimana nanti akan kembali
+    menjadi satu jika di lakukan penjumlahan kuadrat.
+
+    13 = 1^2 + 3^2 = 10 = 1^2 + 0^2 = 1 -> Happy Number
+    4 = 4^2 = 16 = 1^2 + 6^2 = 37 ... 2^2 + 0 = 4 -> Sad Number
+
+    >>> happy_or_sad(23)
+    'happy number'
+    >>> happy_or_sad(44)
+    'happy number'
+    >>> happy_or_sad(8)
+    'sad number'
+    >>> happy_or_sad(20)
+    'sad number'
+    """
+    set_value = set()
+    happy, sad = "happy number", "sad number"
+    while True:
+        if number == 1:
+            return str(happy)
+
+        number = sum_digit(number)
+
+        if number in set_value:
+            return str(sad)
+
+        set_value.add(number)
+
+
+def main(args=None):
+    import doctest
+
+    doctest.testmod()
+
+    # sample case
+    happy_numbers = [1, 7, 23, 31, 44]
+    unhappy_numbers = [2, 3, 8, 20, 4]
+
+    for i in happy_numbers:
+        print(happy_or_sad(i))
+
+    print("\n")
+
+    for i in unhappy_numbers:
+        print(happy_or_sad(i))
+
+
+if __name__ == "__main__" :
+    main()