In the program below, we've used an
if...else statement in combination with a while loop to calculate the sum of natural numbers up to num.
# Sum of natural numbers up to num num = 16 if num < 0: print("Enter a positive number") else: sum = 0 # use while loop to iterate until zero while(num > 0): sum += num num -= 1 print("The sum is", sum)
The sum is 136
Note: To test the program for a different number, change the value of num.
Initially, the sum is initialized to 0. And, the number is stored in variable num.
Then, we used the
while loop to iterate until num becomes zero. In each iteration of the loop, we have added the num to sum and the value of num is decreased by 1.
We could have solved the above problem without using a loop by using the following formula.
For example, if n = 16, the sum would be (16*17)/2 = 136.
Your turn: Modify the above program to find the sum of natural numbers using the formula below.