12.5. Math Methods
As with strings and arrays, JavaScript provides some built-in methods for the
Math

object. These allow us to perform calculations or tasks that are more
involved than simple multiplication, division, addition, or subtraction.

12.5.1. Common Math Methods
The Math

object contains over 30 methods. The table below provides a sample
of the most frequently used options. More complete lists can be found here:

W3 Schools Math Reference
MDN Web Docs
To see detailed examples for a particular method, click on its name.

Ten Common Math Methods
Method
Syntax
Description
abs
Math.abs(number)

Returns the positive value of number

.
ceil
Math.ceil(number)

Rounds the decimal number

UP to the closest integer value.
floor
Math.floor(number)

Rounds the decimal number

DOWN to the closest integer value.
max
Math.max(x,y,z,...)

Returns the largest value from a set of numbers.
min
Math.min(x,y,z,...)

Returns the smallest value from a set of numbers.
pow
Math.pow(x,y)

Returns the value of x raised to the power of y (x ^{y} ).
random
Math.random()

Returns a random decimal value between 0 and 1, NOT including 1.
round
Math.round(number)

Returns number

rounded to the nearest integer value.
sqrt
Math.sqrt(number)

Returns the square root of number

.
trunc
Math.trunc(number)

Removes any decimals and returns the integer part of number

.

12.5.2. Check Your Understanding
Follow the links in the table above for the floor

, random

, round

,
and trunc

methods. Review the content and then answer the following
questions.

Question

Which of the following returns -3

when applied to -3.87

?

Math.floor(-3.87)

Math.random(-3.87)

Math.round(-3.87)

Math.trunc(-3.87)

Question

What is printed by the following program?

let num = Math . floor ( Math . random () * 10 );
console . log ( num );

A random number between 0 and 9.
A random number between 0 and 10.
A random number between 1 and 9.
A random number between 1 and 10.
Question

What is printed by the following program?

let num = Math . round ( Math . random () * 10 );
console . log ( num );

A random number between 0 and 9.
A random number between 0 and 10.
A random number between 1 and 9.
A random number between 1 and 10.