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Python – Find Product of Index Value and find the Summation
• Last Updated : 02 Dec, 2020

Given a List of elements, write a Python program to perform the product of index and value and compute the summation.

Examples:

Input : test_list = [5, 3, 4, 9, 1, 2]
Output : 76
Explanation : 5 + (3*2) 6 + 12 + 36 + 5 + 12 = 76

Input : test_list = [5, 3, 4]
Output : 23
Explanation : 5 + (3*2) 6 + 12 = 23

Method #1: Using loop + enumerate()

In this, we iterate for each element along with its index using enumerate() and compute the product. Sum counter is maintained to update the intermediate sum of the product computed.

## Python3

 `# Python3 code to demonstrate working of``# Index Value Product Sum``# Using loop + enumerate()`` ` `# initializing list``test_list ``=` `[``5``, ``3``, ``4``, ``9``, ``1``, ``2``]`` ` `# printing original list``print``(``"The original list is : "` `+` `str``(test_list))`` ` `res ``=` `0``for` `idx, ele ``in` `enumerate``(test_list):`` ` `    ``# updating summation of required product``    ``res ``+``=` `(idx ``+` `1``) ``*` `ele`` ` `# printing result``print``(``"The computed sum : "` `+` `str``(res))`
Output
```The original list is : [5, 3, 4, 9, 1, 2]
The computed sum : 76```

Method #2 : Using sum() + list comprehension + enumerate()

One liner way to solve this problem, in this, we perform task of getting products iteration as list comprehension and summation at end is done using sum().

## Python3

 `# Python3 code to demonstrate working of``# Index Value Product Sum``# Using loop + enumerate()`` ` `# initializing list``test_list ``=` `[``5``, ``3``, ``4``, ``9``, ``1``, ``2``]`` ` `# printing original list``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# one liner to solve problem using list comprehension``res ``=` `sum``([(idx ``+` `1``) ``*` `ele ``for` `idx, ele ``in` `enumerate``(test_list)])`` ` `# printing result``print``(``"The computed sum : "` `+` `str``(res))`
Output
```The original list is : [5, 3, 4, 9, 1, 2]
The computed sum : 76```

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