sum of first n natural numbers

Author: fazleyazdan

13. logic/beginners/sum_first_natural_num.py

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+# Sum of First N Natural Numbers
+# Problem: Write a Python function that takes an integer n as input and returns the sum of the first n natural numbers.
+# Input: An integer n.
+# Output: The sum of the first n natural numbers.
+
+
+def sum_natural_numbers(n):
+    
+    natural_sum = 0              # for adding natural numbers
+    change_num = 0               # for changing the natural numbers
+    
+    for i in range(n):
+        change_num += 1
+        natural_sum += change_num
+    return natural_sum
+
+print(sum_natural_numbers(4))
+
+
+#! the optimized version
+# we can exclude the 'change_num' 
+
+def sum_natural_numbers1(n):
+    
+    sum = 0         
+    for i in range(1, n+1):      #! why n+1 : Commentary Below
+        sum += i
+    return sum
+