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# Work With Lists of Numbers

**00:00**
In this lesson, you’ll learn some Python tools to work with lists of numbers.

**00:06**
It’s not uncommon that you’ll have to work with a list of numbers. For example, here we have our `numbers`

list again. This time it goes all the way up to five, so it contains the integers from one through five.

**00:16**
And you may want to sum up all of the values that are inside of this list. Now you know that lists are iterable, so you can do this using a `for`

loop.

**00:25**
You could define a variable outside of the loop that’s going to hold the total. So I’m going to say `total = 0`

to initialize the variable, and then start a `for`

loop where I’m going to say `for number in numbers`

**00:40**
and then add them to the total. So I will say `total = total + number`

.

**00:49**
And then at the end, I can print out `total`

and you’ll see that it summed up all of the numbers that are inside of the `numbers`

list.

**00:55**
This is a way you can do it, but Python has some tools that make operations like this one faster and easier because you can perform some mathematical operations on collections using built-in functions.

**01:08**
For example, you have the `sum()`

function, so that does exactly what you expect. It sums up all the items inside of a collection. So I can say `sum()`

and pass it `numbers`

as an argument.

**01:22**
And now if I press *Enter*, you can see I get the exact same result, `15`

again, because the `sum()`

function summed up all the integers that are inside of the `numbers`

list.

**01:32**
So one plus two plus three plus four plus five, and that comes up to 15.

**01:41**
There’s also a `min()`

and the `max()`

function that do what you’d probably also expect them to do. I think they’re very descriptively named.

**01:51**
Let’s try them out in IDLE. So if you say `min()`

and pass it a collection, you’ll get the minimum value in the collection. In the `numbers`

list, that minimum value is `1`

.

**02:02**
And if you type `max()`

, open up parentheses and then type in `numbers`

, close them, press *Enter*, then you get `5`

because that’s the maximum value inside of the `numbers`

list.

**02:13**
If we would add something else, let’s say I would say `numbers.insert()`

and at index two, I’m going to insert `100`

,

**02:26**
and then if I run `max()`

again on the `numbers`

list, I’ll get `100`

as the output because now `100`

is the highest value inside of my `numbers`

list.

**02:37**
So `sum()`

, `min()`

, and `max()`

are some useful built-in functions that you can pass a collection to. And then you can perform some common mathematical operations with them.

**02:49**
And notice that I said collections, so it doesn’t have to be a list. You can do the same thing also with a tuple if you want. You can go ahead and try that out.

**02:57**
It works exactly the same way as it does with lists.

**03:03**
In this lesson, you’ve learned how you can work with lists of numbers using some common built-in Python functions. In the next lesson, you’ll look at something quite powerful and interesting called list comprehensions.

**03:15**
You may have seen those around or heard about them. In the next lesson, we’ll uncover together what list comprehensions are and how we can use them in Python.

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