Add Armstrong number algorithm in maths module

Author: Manvith-kumar16

maths/armstrong_number.py

@@ -0,0 +1,16 @@
+def is_armstrong(number: int) -> bool:
+    """
+    Check if a number is an Armstrong number.
+
+    >>> is_armstrong(153)
+    True
+    >>> is_armstrong(123)
+    False
+    """
+    digits = list(map(int, str(number)))
+    power = len(digits)
+    return sum(d ** power for d in digits) == number
+
+
+if __name__ == "__main__":
+    print(is_armstrong(153))