# Python Program to Find Sum of n Numbers

Python program to find sum of n numbers; In this tutorial, you will learn how to find or calculate sum of n numbers using for loop, while loop and function.

## Python Program to Calculate Sum of n Numbers

• Calculate/Find the sum of n natural numbers using loop and range function.
• Find/Calculate Sum of n natural numbers in python using while loop
• Python program to find/calculate the sum of numbers in a given list
• The mathematical formula to find/calculate the sum of n numbers with python program
• Python Program to Find/Calculate sum of n odd natural numbers.
• Python Program to Find/Calculate sum of n even natural numbers.

### 1: Find/Calculate the sum of n natural numbers using loop and range function

• First of all, you can use a python input() function in your python program that takes a user to enter the number (n) to calculate the sum.
• Next, declare a variable that name sum, it will contain sum of n natural numbers sum.
• Next, run loop till the entered number using the for loop and range() function.
• Inside a loop, calculate the sum of n numbers using a `sum = sum + current number` formula.
• After the loop ends, print the sum variable that contains the sum of n numbers
```n = input("Enter Number to calculate sum")
n = int (n)
sum = 0
for num in range(0, n+1, 1):
sum = sum+num
print("SUM of first ", n, "numbers is: ", sum )
```

Output:

```Enter Number to calculate sum 5
Sum of first 5 number is: 15```

### 2: Find/Calculate Sum of n natural numbers in python using while loop

Also, use the while loop in python to calculate the sum of n numbers.

• First of all, you can use a python input() function in your python program that takes a user to enter the number (n) to calculate the sum.
• Next, declare a variable that name sum, it will contain the sum of n natural numbers sum.
• Run while loop until n is greater than zero
• Add the current value of n to sum variable. And, decrement n number by 1 in while loop body
• After the loop finishes, the print sum name variable.

#### Python program to find the sum of n numbers using While loop:

```n = input("Enter Number to calculate sum")
n = int (n)
total_numbers = n
sum=0
while (n >= 0):
sum += n
n-=1
print ("sum using while loop ", sum)
```

Output:

```Enter Number to calculate sum 5
Sum using while loop  15 ```

### 3: Python program to Find/Calculate the sum of numbers in a given list

• Declare a variable that name sum, it will contain the sum of n natural numbers sum.
• Next, define list and assign a value to a python list.
• Run for a loop and Add the current value of n to sum variable.
• After the loop finishes, the print sum name variable.
```sum = 0
list = [11,4,5,7,99,10,12]
for num in list:
sum = sum +num
print ("sum of list element is : ", sum)
```

Output:

`sum of list element is :  148 `

### 4: The mathematical formula to Find/Calculate the sum of n numbers with python program

In the above programs, you have learned how to calculate the sum of n numbers using for loop, while loop and range function.

Now, you will learn how to calculate/find sum of n numbers in python without for loop, while loop in python. Calculate the sum directly using a mathematical formula in python program.

The sum of the n natural number mathematical formula is = `n * (n+1) / 2`.

In the below python program, you will learn how to use this mathematical formula is = `n * (n+1) / 2` to find/calculate sum of n numbers in python programs.

• Take a input from user in your python program using input() function.
• Convert a user inputted number to an integer using int() function.
• Calculates sum of number by using this formula `n * (n+1) / 2` in your python program.
• After that, the print name sum variable.
```n = input("Enter a number to calculate sum")

n = int (n)
sum = n * (n+1) / 2
print("Sum of fthe irst ", n, "natural numbers using formula is: ", sum )
```

Output:

```Enter a number to calculate sum 5
Sum of fthe irst  5 natural numbers using formula is:  15.0 ```

### 5: Python Program to Find/Calculate sum of n odd natural numbers

• Take input from user using python input() function in your python program.
• Next, declare a variable that name sum, it will contain the sum of n odd numbers.
• Next, run loop till the entered number using the for loop and range() function.
• Inside a loop, calculate the sum of n odd numbers using a `sum = sum + current number` formula with (not (num % 2) == 0).
• After the loop ends, print the sum variable that contains the sum of n odd numbers.

#### Python program to find sum of n odd numbers:

```n = input("Enter Number to calculate sum")
n = int (n)
sum = 0
for num in range(0, n+1, 1):

if(not (num % 2) == 0):
sum += num;

print("SUM of odd numbers is: ", sum )
```

Output:

```Enter Number to calculate sum 5
SUM of odd numbers is:  9 ```

### 6: Python Program to Find/Calculate sum of n even natural numbers

• Take input from the user using python input() function in your python program.
• Next, declare a variable that name sum, it will contain the sum of n even numbers.
• Next, run loop till the entered number using the for loop and range() function.
• Inside a loop, calculate the sum of n even numbers using a `sum = sum + current number` formula with if test condition ((num % 2) == 0).
• After the loop ends, print the sum variable that contains the sum of n even numbers.

#### Python program to find sum of n even numbers:

```n = input("Enter Number to calculate sum")
n = int (n)
sum = 0
for num in range(0, n+1, 1):

if((num % 2) == 0):
sum += num;

print("SUM of even numbers is: ", sum )
```

Output:

```Enter Number to calculate sum 5
SUM of even numbers is:  9 ```

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