# How to Multiply List Elements by a Number – Top 5 Ways

## Problem Formulation and Solution Overview

In this article, you’ll learn how to multiply List Elements by a Number in Python.

This example multiples the first five (5) Prime Numbers by two (2) and return the result.

π¬ Question: How would we write Python code to multiply the list elements?

We can accomplish this task by one of the following options:

## Method 1: Use List Comprehension

This method uses `List Comprehension` to apply a mathematical operation to each element and return the result.

```prime_nums = [2, 3, 5, 7, 11]
mult_result = [x * 2 for x in prime_nums]
print(mult_result)```

Above declares the first (5) Prime Numbers and saves this `List` to `prime_nums`. Next, `List Comprehension` loops through each element and applies the multiplication operation to each. The output saves to `mult_result` and is output to the terminal.

## Method 2: Use Pandas tolist()

This method requires an additional library to be imported, `Pandas`, to use the `tolist()` function.

```import pandas as pd

prime_nums  = [2, 3, 5, 7, 11]
mult_result = pd.Series(prime_nums)
mult_result = (mult_result*2).tolist()
print(mult_result)```

Above, imports the `Pandas` Library. Click here if this requires installation. Then, the first (5) Prime Numbers are declared and saved to `prime_nums`.

Next, `prime_nums` is passed as an argument to the `pd.Series()` function and returns `mult_result`. The output of `mult_result` at this point is shown below.

Now, we need to convert this output to a list (`tolist()`) and apply the multiplication operation to each element. The results save to `mult_result` and are output to the terminal.

## Method 3: Use map and lambda Functions

This method wraps the `map()`, and `lambda` functions inside a Python `List` and calculates the results.

```prime_nums = [2, 3, 5, 7, 11]
mult_result = list(map(lambda x: x*2, prime_nums))
print(mult_result)```

Above declares the first (5) Prime Numbers and saves them to `prime_nums`. The next line does the following:

Then, `mult_result` is output to the terminal.

## Method 4: Use Numpy Array()

This method requires an additional library to be imported, NumPy, to use the `np.array()` function.

```import numpy as np
prime_nums = [2, 3, 5, 7, 11]
the_result = list(np.array(prime_nums) * 2)
print(the_result)```

Above, imports the NumPy Library. Click here if this requires installation. Then the first (5) Prime Numbers are declared and saved to `prime_nums`.

Next, `prime_nums` is passed as an argument to `np.array()` where the multiplication operation is applied to each element. Then, this is converted to a List, saved to `the_result` and output to the terminal.

## Method 5: Use Slicing

This method uses Python’s infamous `Slicing`! No overhead, and a very pythonic way to resolve the issue.

```prime_nums = [2, 3, 5, 7, 11]
prime_nums[:] = [x * 2 for x in prime_nums]
print(prime_nums)```

Above declares the first (5) Prime Numbers and saves them to `prime_nums`.

Then slicing is applied and used in conjunction with `List Comprehension` to apply the multiplication operation to each element. The results save back to `prime_nums` and are output to the terminal.

πA Finxter Favorite!

## Summary

These methods of multiplying list elements by a number should give you enough information to select the best one for your coding requirements.

Good Luck & Happy Coding!

## Programmer Humor

π±ββοΈ Programmer 1: We have a problem
π§ββοΈ Programmer 2: Letβs use RegEx!
π±ββοΈ Programmer 1: Now we have two problems

… yet – you can easily reduce the two problems to zero as you polish your “RegEx Superpower in Python“. π