*The Python sum() function calculates the total of all numerical values in an iterable. sum() works with both integers and floating-point numbers. The sum() function has an optional parameter to add a number to the total.*

alculating the sum of a list is a common operation in Python. For example, let’s say you are a coffee shop owner who wants to know the total value of all sales made last month. You could use the *sum()* function to perform this calculation.

In Python code, the *sum()* function can be used to calculate the sum of all values in an iterable object. This method is useful when you need the total value of a list of items, which is common in a number of mathematical calculations.

In this tutorial, we are going to discuss how to use the Python *sum()* method. We’ll go through a few examples to showcase how this method works in a real program.

## Python Sum Syntax

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The Python sum() function adds up all the numerical values in an iterable, such as a list, and returns the total of those values. sum() calculates the total of both floating-point numbers and integers.

For instance, you could use the *sum()* method to calculate the total price of the products a customer purchases at a store.

Here’s the syntax for the Python *sum()* method:

sum(iterable_object, start_value)

The function *sum()* takes in two parameters:

- The iterable object that you would like to calculate the total of (required)
- An extra number that you want to add to the value you’re calculating (optional)

Let’s use an example to illustrate how the Python *sum()* function works.

## Sum Python Example

Let’s say that we operate a local store and want to calculate the total amount to charge a customer for their shopping. We already have a list containing the prices of each individual product, but now we want to get the total value of that list.

We could use the *sum()* function for this purpose. Here’s an example of the *sum()* function being used to calculate the total cost of a customer’s shopping:

products_purchased = [5.40, 2.20, 9.95, 1.50, 1.50, 2.20, 4.65, 3.00, 2.00] total_price = sum(products_purchased) print(total_price)

Our program returns the sum: 32.40. Let’s break down our code and discuss how it works.

On the first line, we declare a Python variable called *products_purchased* which stores the prices of each product a customer has purchased.

On the next line, we calculate the total price of the customer’s shop by using the *sum()* function on our *products_purchased* Python array. Next, our program prints out the total price of the customer’s shop that has been calculated using *sum()*.

### Python Sum Function: Using a Tuple

In the above example, we have used *sum()* to calculate the total value of several items in a list. But if our values were stored in a Python tuple, we could also have used *sum()*. Here’s an example of *sum()* being used to calculate the total value of a tuple:

products_purchased = (5.40, 2.20, 9.95, 1.50, 1.50, 2.20, 4.65, 3.00, 2.00) total_price = sum(products_purchased) print(total_price)

Our code returns: 32.40. This program is almost exactly the same as the one above. The only difference being that our *products_purchased* variable has been assigned a tuple rather than a list.

## sum in Python Second Argument

The *sum()* function takes in an optional second parameter which adds a number to the final total calculated by the method.

Let’s say that a customer has decided to purchase a bag after their groceries have been scanned. Each bag costs $1. To add the $1 bag to the customer’s total, you could specify a second parameter in the *sum()* method.

Here’s the code that we could use to calculate the price of a customer’s purchase, in addition to the $1 bag they have bought:

products_purchased = [2.00, 3.00, 4.00] total_price = sum(products_purchased, 1.00) print(total_price)

Our program returns: 10.00. When our final value *1* is added to the *sum()* method, it is added and so our program returns 10.00.

## Conclusion

The *sum()* method can be used in Python to calculate the total of the items stored in an iterable object. For example, *sum()* could be used to calculate the cost of your coffee shop order.

In this tutorial, we explored how to use the *sum()* function in Python. Then, we discussed how to use the second parameter offered by *sum()* to add more values to the total calculation. Now you’re equipped with the knowledge you need to use the *sum()* method in Python like a pro!

To learn more about coding in Python, read our How to Learn Python guide.

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