Collatz sequence and Factorial Added

PYTHON/ProblemsAndSolutions/collatz_sequence.py

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+#  collatz_sequence.py
+"""
+Description:
+This is a mathematical phenomenon whereby starting with any number,
+it will always stop at 1 using the following mathematical concepts.
+base number = ?
+if the base number is even; divide it by 2, and the answer,
+reassign it to the base number
+else 3 * base number + 1
+For more explanation:
+Collatz conjecture. (2022, October 9). In Wikipedia. https://en.wikipedia.org/wiki/Collatz_conjecture
+"""
+
+
+def collatz(number: int) -> int:
+    # It stops when the number equals 1.
+    while number != 1:
+        if number % 2 == 0:
+            number //= 2
+        else:
+            number = 3 * number + 1
+        print(number, end=" ")
+
+
+response: int = int(input("Enter a number: ").strip())
+collatz(response)

PYTHON/ProblemsAndSolutions/factorial.py

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+# fibonacci.py
+"""
+Factorial is a mathematical function of f(n!):
+Mathematical formulae: n * (n - 1)!
+Further explanation: Factorial. (2022, October 4).
+In Wikipedia. https://en.wikipedia.org/wiki/Factorial
+"""
+
+
+def factorial(starting_number: int) -> int:
+    if starting_number == 0 or starting_number == 1:
+        return 1
+
+    #  This is a recursive call: where it multiplies the previous with now - 1
+    fib = starting_number * factorial(starting_number - 1)
+    return fib
+