We can perform arithmetic on variables storing numbers similar to how we perform operations on raw numerical values.

**For example:**

let varA = 10;
let varB = 20;

console.log(varA + varB);

The expression `varA + varB` considers `varA` and `varB` as if they were raw numbers.

The right-hand side of the assignment statement is always evaluated before feeding the result into the variable on the left side. Because of this, we can make changes to the value of a variable:


let exampleVar = 100;
console.log(exampleVar); // Before
exampleVar = exampleVar + 100;
console.log(exampleVar); // After

This above code adds 100 to the value of `exampleVar`.

However, the same operation can also be performed using a shorter syntax:

let exampleVar = 100;
exampleVar += 100;
console.log(exampleVar);

This syntax works for any supported arithmetic operation.

**For example:**

exampleVar *= 100; // Multiplication
exampleVar /= 100; // Division
exampleVar **= 100; // Raising to a Power
exampleVar %= 100; // Remainder

A short syntax for **incrementing** the value of a variable by `1` is by using the `++` operator. For-example:

let varA = 9;
console.log(varA); // Before
varA++;
console.log(varA); // After

We can use `--` for **decrementing** a variable by `1`:

let varA = 5;
console.log(varA); // Before
varA--;
console.log(varA); // After

What is the purpose of the following line of code?

Which of the following is the correct shorthand for the operation `exampleVar = exampleVar - 50`?

In this section, we will get an introduction to JavaScript by looking at the basic syntax of the language, along with a few terms and concepts which will build our foundation for learning more advanced features of the language in the upcoming section. This section will include hands-on tasks which will help you practice all the concepts and remember the contents naturally without effort.

In this section, we will look at how to store some data and retrieve it later on using Variables. Moreover, we will explore some basic data types and look at how they interact with each other.

In this chapter we will look at how to write expressions which evaluate to "true" or "false" based on the conditions, for example "Is X equal to Y?". Afterwards, we will build on that concept and learn to write "Conditional Statements" which will enable us to conditionally execute specific lines of code.

Introduction to JavaScript

Performing Arithmetic On Variables

1. What will the following code output?

2. What is the purpose of the following line of code?

3. Which of the following is the correct shorthand for the operation `exampleVar = exampleVar - 50`?