JavaScript Arithmetic Operator
In this tutorial, you will learn about arithmetic operators in javascript with examples.
Arithmetic Operators
Arithmetic operators are the set of operators that performs mathematical operations on the operands like addition, subtraction, multiplication, division, etc.
Some of the arithmetic operators behave differently in different contexts. For example, the addition operator (+) adds 2 numbers but concatenate two strings.
There are the following arithmetic operators in javascript.
Operators  Sign  Description  Example 

Addition  +  Adds 2 numbers and concatenates 2 strings. 

Subtraction    Subtracts 2 numbers 

Multiplication  *  Multiplies 2 numbers 

Division  /  Divides 2 numbers 

Modulus  %  Returns the remainder of the division of 2 numbers 

Exponent  **  Returns the result of the first number raised to the power of the second number 

Floor Division  //  Returns the floor of the division of 2 numbers 

Let's discuss each operator and see their examples.
1. Addition operator
Addition operator is used to add two operands. To add operands use +
symbol. for example 10 + 15
or we can add variable var a = 5, b = 1, c; c = a + b;
.
Example
var x = 10 + 15; // adding numbers
var y = 2.5 + 3.4; // float number
console.log(x, y);
var a = 5, b = 10, c;
c = a + b; // adding variables
var d = (1 + 2 + 3 + 4 + 5) * c; // addition in expression
console.log(d);
▶ Run the code
Concatenating String using + operator
The same operation sign +
can concatenate strings also, which means it can attaching two strings side by side. For example, var greeting = "Hello," + " World!"
output is Hello, World!.
Example
var a = "Hello," + " World";
var x = "tutorials";
var y = "tonight";
var z = ".com";
var b = x + y + z;
console.log(a, b);
▶ Run the code
Adding Strings and numbers
Javascript behaves strangely sometimes. It can add number string (like '2', '4.5', '10', etc) with actual number (Data type  Number) and give string value. For example, var a = 5 + '5'
is a valid expression and gives a string result.
Output of adding number string and numbers depends on orientation of operators. Javascript adds all numbers first and when it comes first string then it starts concatenating all coming operands. For example 2 + '2' = "22"
, 2 + 2 + '2' = "42"
, 2 + 2 + '2' + 1 = "421"
and so on.
Example
var a = 2 + 2; // 4
var b = 2 + 2 + '2'; // 4 + '2' = "42"
var c = 10 + 5 + '5' + 5; // 15 + '5' + 5 => "155" + 5 => "1555"
console.log(a, b, c);
console.log(typeof a, typeof b, typeof c);
▶ Run the code
2. Subtraction operator
Subtraction operator is used to subtract two operands. To subtract operands use 
symbol. for example 10  15
or we can subtract variable var a = 5, b = 1, c; c = a  b;
.
Example
var x = 20  15;
var y = 9.5 + 3.4; // float number
var a = 5, b = 10, c;
c = a  b; // Subtracting variables
var d = (12  4  5) * c; // Subtracting in expression
console.log(x, y, d);
▶ Run the code
Subtracting numerical string
Unlike the addition operator which adds and concatenates both, the subtraction operator always subtracts.
Example
var a = 5  10; // 5
var b = 12  2  '2'; // 10  '2' = 8
console.log(a, b);
▶ Run the code
3. Multiplication operator
The multiplication operator is used to multiply two operands. To multiply operands use the *
symbol. for example 10 * 15
or we can multiply variable var a = 5, b = 1, c; c = a * b;
.
Example
var a = 5 * 2; // 10
var b = 6.1;
var c = 3.2;
var d = b * c; // 19.52
console.log(a, d);
▶ Run the code
4. Division operator
Division operator is used to divide two operands. To divide operands use /
symbol. for example 10 / 15
or we can divide variable var a = 5, b = 1, c; c = a / b;
.
Example
var a = 16 / 2; // 8
var b = 21;
var c = 7;
var d = b / c;
console.log(a, d);
▶ Run the code
5. Modulus operator
The modulus operator is used to find the remainder of the division. To find the remainder of the division uses the %
symbol. for example 10 % 3
or we can find remainder of variable var a = 5, b = 1, c; c = a % b;
.
Example
var a = 17 % 2; // 1
var b = 13;
var c = 7;
var d = b % c;
console.log(a, d);
▶ Run the code
6. Exponential operator
The exponential operator is used to raise one operand to the power of another. To raise operands use the **
symbol. for example 10 ** 2
or we can raise variable var a = 5, b = 1, c; c = a ** b;
.
Javascript also has Math.pow(a,b) method to find exponentials.
Example
var a = 5 ** 2; // 5^2 = 25
var b = 3;
var c = 4;
var d = b ** c;
console.log(a, d);
▶ Run the code
7. Floor division operator
Floor division operator is used to find quotient of division. To find quotient of division use //
symbol. for example 10 // 3
or we can find quotient of variable var a = 5, b = 1, c; c = a // b;
.
Example
var a = 17 // 2; // 8
var b = 13;
var c = 7;
var d = b // c;
console.log(a, d);
Increment operator
Increment operator ++
is used to increase a number by 1.
Increment operator can be used in two ways:
 preincrement: When Increment operator is used before the operand. Example 
++a;
 postincrement: When Increment operator is used after the operand. Example 
a++;
Difference in preincrement and postincrement : Both increase operand by 1 but preincrement increase value before assigning value to the operand but postincrement increase value after assigning value to number. For example var a = 10; console.log(a++); // output 10 not 11
and var a = 10; console.log(++a); // output 11
.
Example
var a = 10;
var b = 15;
var c = 12;
console.log(b + a++); // 15 + 10 = 25
console.log(a); // 11
// a = 11 now but first b + a was added then a was increased
console.log(b + ++a); // 15 + 12 = 27)
console.log(c++); // output: 12
▶
Run the code
Decrement operator
Decrement operator 
is used to decrease a number by 1.
Decrement operator can be used in two ways:
 predecrement : When the decrement operator is used before the operand. Example 
a;
 postdecrement : When decrement operator is used after the operand. Example 
a;
The difference in predecrement and postdecrement: Both decrease operand by 1 but predecrement decrease value before assigning value to the operand but postdecrement decrease value after assigning value to a number. For example var a = 10; console.log(a); // output 10 not 9
and var a = 10; console.log(++a); // output 9
.
Example
var a = 10;
var b = 15;
var c = 12;
console.log(c); // output: 12
console.log(b + a); // 15 + 10 = 25
console.log(a); // 9
// a = 9 now but first b + a was added then a was decreased
console.log(b + a); // 15 + 8 = 23)
▶
Run the code