  # sum () function in python The sum of the numbers in the list is required everywhere. Python provides a built-in function sum () that sums the numbers in a 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. `

Two syntaxes are possible:

`  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 implementation of sum () in Python

 ` # Python code to demonstrate how it works ` ` # sum () `   ` numbers ` ` = ` ` [` ` 1 ` `, ` ` 2 ` `, ` ` 3 ` `, ` ` 4 ` `, ` ` 5 ` `, ` ` 1 ` `, ` ` 4 ` `, ` ` 5 ` `] `   < code class = "comments"> # no launch parameter specified ` Sum ` ` = ` ` sum ` ` (numbers) ` ` print ` ` (` ` Sum ` `) `   ` # start = 10 ` ` Sum ` ` = ` ` sum ` ` (numbers, ` ` 10 ` `) ` ` print ` ` (` ` Sum ` `) `

Output:

` 25 35 `

Errors and exceptions

error type: this error occurs if the list contains something other than digits.

 ` # Python code to demonstrate the exception ` ` # sum () `` arr = [ "a" ]   # no launch parameter specified Sum = sum (arr) print ( Sum )   # start = 10 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 must contain numbers

Practical Application: problems when we need to calculate the amount to perform further operations, such as determining the average.

 ` # Python code to demonstrate practical use ` ` Amount # () ` ` `  ` nu mbers ` ` = ` ` [` ` 1 ` `, ` ` 2 ` `, ` ` 3 ` `, ` ` 4 ` `, ` ` 5 ` `, ` ` 1 ` `, ` ` 4 ` `, ` ` 5 ` `] `   ` # start = 10 ` ` Sum ` ` = ` ` sum ` ` (numbers) ` ` average ` ` = ` ` Sum ` ` / ` ` len ` ` (numbers) ` ` p rint ` ` average `

Output:

` 3 `