# 30 Days Of JavaScript

## Day 1: Simple Types

### Lesson 5: Numbers

We can store numbers in variables as well.

``1const myAge = 35;``

Of course in this case my age changes every year so we shouldn't store it as a const if we want to increase it. We should use a variable instead.

``````1let myAge = 35;
2myAge = myAge + 1;``````

You can see here I have taken `myAge` added `1` to it and set the new value to `myAge` this is very common and totally ok todo in JavaScript. The code to the right of the `=` runs and then the result is stored in `myAge`

Test this yourself in the play ground below:

Was this what you expected? `myAge` starts at 35, we then add 1 to it so it goes to 36. So in that final calculation we do `36 + 36 + 1` which is 73.

All mathematical operators are available to us:

``````1const add = 3 + 5;
2const subtract = 3 - 4;
3const multiply = 3 * 3;
4const divide = 3 / 2;``````

JavaScript will even handle negative and decimal numbers for us with no problem. So the result of subtract and divide above won't cause a problem and can be used in further calculations as well (this isn't the case in all programming languages).

There is one more handy mathematical operator I want to talk about here, the modulo operator. This is like divide but it gives you the remainder as a number. Which sounds weird and useless but it gets used more than you would think, and is a key part of solving a well known interview questions called Fizz Buzz.

Let's take a look, `heightOfBrick` and `heightOfWallNeeded` are both in cm, by using the modulo operator we find out that the last brick row height will have to be 9 cm

Take a minute to use this playground to work something out. Maybe how to convert from one type of measurement units (like cm) to another (such as inches).

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