How do you add the sum of a number in python?

Question

In this program, you will learn to add two numbers and display it using print() function.

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Example 1: Add Two Numbers
Example 2: Add Two Numbers With User Input
sum() Syntax
sum() Parameters
sum() Return Value
Example: Working of Python sum()
How do you sum up a specific number in Python?
What is the += in Python?
What does sum () do in Python?
How do you find the sum of n numbers in Python?

To understand this example, you should have the knowledge of the following Python programming topics:

Python Input, Output and Import
Python Data Types
Python Operators

In the program below, we've used the + operator to add two numbers.

Example 1: Add Two Numbers

# This program adds two numbers

num1 = 1.5
num2 = 6.3

# Add two numbers
sum = num1 + num2

# Display the sum
print('The sum of {0} and {1} is {2}'.format(num1, num2, sum))

Output

The sum of 1.5 and 6.3 is 7.8

The program below calculates the sum of two numbers entered by the user..

Example 2: Add Two Numbers With User Input

# Store input numbers
num1 = input('Enter first number: ')
num2 = input('Enter second number: ')

# Add two numbers
sum = float(num1) + float(num2)

# Display the sum
print('The sum of {0} and {1} is {2}'.format(num1, num2, sum))

Output

Enter first number: 1.5
Enter second number: 6.3
The sum of 1.5 and 6.3 is 7.8

In this program, we asked the user to enter two numbers and this program displays the sum of two numbers entered by user.

We use the built-in function input() to take the input. Since, input() returns a string, we convert the string into number using the float() function. Then, the numbers are added.

Alternative to this, we can perform this addition in a single statement without using any variables as follows.

print('The sum is %.1f' %(float(input('Enter first number: ')) + float(input('Enter second number: '))))

Output

Enter first number: 1.5
Enter second number: 6.3
The sum of 1.5 and 6.3 is 7.8

Although this program uses no variable (memory efficient), it is harder to read.

The sum() function adds the items of an iterable and returns the sum.

Example

marks = [65, 71, 68, 74, 61]

# find sum of all marks
total_marks = sum(marks)
print(total_marks)

# Output: 339

sum() Syntax

The syntax of the sum() function is:

sum(iterable, start)

The sum() function adds start and items of the given iterable from left to right.

sum() Parameters

iterable - iterable (list, tuple, dict, etc). The items of the iterable should be numbers.
start (optional) - this value is added to the sum of items of the iterable. The default value of start is 0 (if omitted)

sum() Return Value

sum() returns the sum of start and items of the given iterable.

Example: Working of Python sum()

numbers = [2.5, 3, 4, -5]

# start parameter is not provided
numbers_sum = sum(numbers)
print(numbers_sum)

# start = 10
numbers_sum = sum(numbers, 10)
print(numbers_sum)

Output

4.5
14.5

If you need to add floating-point numbers with exact precision, then you should use math.fsum(iterable) instead.

If you need to concatenate items of the given iterable (items must be strings), then you can use the join() method.

'string'.join(sequence)

Visit this page to learn about, Python join() Method

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Sum of numbers in the list is required everywhere. Python provides an inbuilt function sum() which sums up the numbers in the list.

Syntax:

sum(iterable, start)  
iterable : iterable can be anything list , tuples or dictionaries ,
 but most importantly it should be numbers.
start : this start is added to the sum of 
numbers in the iterable. 
If start is not given in the syntax , it is assumed to be 0.

Possible two syntaxes:

sum(a)
a is the list , it adds up all the numbers in the 
list a and takes start to be 0, so returning 
only the sum of the numbers in the list.
sum(a, start)
this returns the sum of the list + start

Below is the Python implementation of the sum()

Python3

numbers = [1,2,3,4,5,1,4,5]

Sum = sum(numbers)

print(Sum)

Sum = sum(numbers, 10)

print(Sum)

Output:

25
35

Error and Exceptions

TypeError : This error is raised in the case when there is anything other than numbers in the list.

Python3

arr = ["a"]

Sum = sum(arr)

print(Sum)

Sum = sum(arr, 10)

print(Sum)

Runtime Error :

Traceback (most recent call last):
  File "/home/23f0f6c9e022aa96d6c560a7eb4cf387.py", line 6, in 
    Sum = sum(arr)
TypeError: unsupported operand type(s) for +: 'int' and 'str'

So the list should contain numbers Practical Application: Problems where we require sum to be calculated to do further operations such as finding out the average of numbers.

Python3

numbers = [1,2,3,4,5,1,4,5]

Sum = sum(numbers)

average= Sum/len(numbers)

print (average)

Output:

How do you sum up a specific number in Python?

Python provides an inbuilt function sum() which sums up the numbers in the list. Syntax: sum(iterable, start) iterable : iterable can be anything list , tuples or dictionaries , but most importantly it should be numbers.

What is the += in Python?

The Python += operator lets you add two values together and assign the resultant value to a variable. This operator is often referred to as the addition assignment operator.