# How to round Off a number upto 2 decimal places using JavaScript?

**JavaScript | Math.round() Method Example**: Here, we are going to learn **how to round Off a number upto 2 decimal places using JavaScript?**

Submitted by Siddhant Verma, on January 21, 2020

There are **various methods of rounding off a number upto 2 decimal places in JavaScript** but the simplest is using the **Math.round() method**. We already know that the Math object has a lot of methods attached to it which we can use for carrying out calculations and one of them is **Math.round()**.

**Math.round()** takes in one parameter, the number to be rounded and returns the nearest integer value of that number.

let b = 10.9; console.log(b); console.log(Math.round(b));

**Output**

10.9 11

**10.9** is rounded off as **11** by **Math.round()** since the nearest integer to **10.9** is **11**.

let c = 10.3; console.log(c); console.log(Math.round(c));

**Output**

10.3 10

**10.3** is rounded off to **10** as it's the nearest integer is **10**.

So, **how can we use Math.round() to round off a number upto 2 decimal places?**

Let's say we have a number **10.1234** rounding this number off to 2 decimal places would yield us **10.12** so let's try to derive a formula using **Math.round()** which can help us achieve it,

var num = 10.1234; console.log(num);

**Output**

10.1234

If we multiply **10.1234** by **100** it gives us **1012.34**

console.log(num*100);

**Output**

1012.34

What if we round this number now?

console.log(Math.round(num*100))

**Output**

1012

Can you see that we're close to our answer here, the only thing we need to do is to put the decimal point by looking at our original number. Since the original number had a decimal after two digits from the beginning, let's place a decimal point after two digits by dividing our number by 100.

console.log(Math.round(num*100)/100);

**Output**

10.12

Voila! We got the number we wanted. Let's look at the formula we derived,

roundedNumber=Math.round(originalNumber*100)/100;

If we had to round this number to 3 decimal places, we would first multiply our number by 1000 and then after rounding it using **Math.round()** divide it by 1000.

In general,

roundedNumber=Math.round(originalNumber*10^i)/10^i;

Where, i is the number of decimal places to be rounded off.

var num = 10.1234; console.log(num); var roundedNum = Math.round(num * 100) / 100; console.log(roundedNum);

**Output**

10.1234 10.12

Let's create a simple function which performs this calculation for us.

function roundoff_2(num) { return Math.round(num * 100) / 100; } console.log(roundoff_2(77.6345));

**Output**

77.63

Let's check if this function returns the same for **10.1234**

console.log(roundoff_2(10.1234));

**Output**

10.12

Can you implement your function which also takes in the number of decimal places to be rounded off and returns the number rounded off to those many numbers of decimal places?

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