Logic Building/Phase 2 - Level 1: Basic Looping/Program

Sum of First N Natural Numbers

Print the sum of first n natural numbers.

Logic BuildingBeginner
Logic Building
# Take n as input
n = int(input("Enter n: "))

# Calculate sum
sum = 0
for i in range(1, n + 1):
    sum += i

print(f"Sum of first {n} natural numbers: {sum}")

Output

Enter n: 5
Sum of first 5 natural numbers: 15

Accumulate sum by adding each number.

Key Concepts:

  • Initialize sum to 0
  • Loop from 1 to n
  • Add each number to sum
  • Formula: n * (n + 1) / 2 (but we use loop)
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