JavaScript Round Numbers to 2, 3, 4 Decimal Places

The 2 simple methods to round numbers to 2 3 4 decimal places in JavaScript are toFixed() and Math.random() in built functions.

When working with numbers in JavaScript, you may often need to round them to a specific number of decimal places.

In this article, we will explore how to round numbers to 2, 3, and 4 decimal places using JavaScript.

Method 1: Using toFixed() Method

JavaScript provides the toFixed() method, which allows you to round a number to a specified number of decimal places and obtain a string representation of the rounded value.

The syntax for using toFixed() is as follows:

number.toFixed(decimalPlaces);
Code language: CSS (css)

Here, number is the original number you want to round, and decimalPlaces is the desired number of decimal places you want to round to.

Let’s look at an example to round a number to 2 decimal places:

var number = 3.14159;
var roundedNumber = number.toFixed(2); // "3.14"
Code language: JavaScript (javascript)

In the above example, number.toFixed(2) returns the string "3.14", which represents the rounded value of 3.14159 to 2 decimal places.

Similarly, you can round a number to 3 or 4 decimal places by adjusting the decimalPlaces argument accordingly.

Here are examples for rounding to 3 and 4 decimal places:

var number = 3.14159;
var roundedNumber3 = number.toFixed(3); // "3.142"
var roundedNumber4 = number.toFixed(4); // "3.1416"
Code language: JavaScript (javascript)

In the above examples, number.toFixed(3) returns the string "3.142", rounding 3.14159 to 3 decimal places, and number.toFixed(4) returns the string "3.1416", rounding it to 4 decimal places.

It’s important to note that the toFixed() method returns a string representation of the rounded number, not a numeric value.

If you need to perform further calculations with the rounded number, you may need to convert it back to a number using parseFloat() or Number() functions.

var number = 3.14159;
var roundedNumber2 = parseFloat(number.toFixed(3)); 
 // 3.14 is now numberCode language: JavaScript (javascript)

Method 2: Using Math.round() Function

If you prefer to round a number to a specific number of decimal places and obtain a numeric value instead of a string, you can use the Math.round() function.

The Math.round() function rounds a number to the nearest integer.

By multiplying and dividing the number by the appropriate factor, we can achieve rounding to a specific number of decimal places.

Let’s see how we can round a number to 2 decimal places using Math.round():

var number = 3.14159;
var roundedNumber = Math.round(number * 100) / 100; 
// 3.14  output
Code language: JavaScript (javascript)

In the above example, we multiply the number by 100 to shift the decimal places two positions to the right. We then use Math.round() to round it to the nearest integer.

Finally, we divide the result by 100 to restore the original scale, giving us the rounded value of 3.14159 to 2 decimal places.

Similarly, you can round a number to 3 or 4 decimal places by adjusting the multiplication and division factors accordingly:

var number = 3.14159;

// Rounding to 3 decimal places
var roundedNumberThree = Math.round(number * 1000) / 1000;
 // 3.142  output

// Rounding to 4 decimal places
var roundedNumberFour = Math.round(number * 10000) / 10000;
  // 3.1416 output
Code language: JavaScript (javascript)

In the above examples, Math.round(number * 1000) / 1000 rounds 3.14159 to 3 decimal places, and Math.round(number * 10000) / 10000 rounds it to 4 decimal places.

Remember, when using Math.round() for rounding to a specific number of decimal places, the multiplication and division factors should be powers of 10 to shift the decimal places accordingly.

Conclusion

Rounding numbers to a specific number of decimal places is a common requirement in JavaScript programming.

In this article, we explored two methods to round numbers in javascript to 2 3 4 decimal places according to our needs.

By using the toFixed() method and the Math.round() function.

Thanks!

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