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:

<h1>Hello World<h1>

let myAge = 35;
console.log(myAge);

myAge = myAge + 1;
console.log(myAge);

myAge = myAge + myAge + 1;
console.log(myAge);

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

<h1>Hello World<h1>

const heightOfBrick = 25;
const heightOfWallNeeded = 484;
const finalRowHeight = heightOfWallNeeded % heightOfBrick;

console.log(finalRowHeight);

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).