Number and Math

Learn Number methods and the Math object.

Number and Math

In JavaScript, all numbers are of type number; there is no separate integer and decimal type. The Math object provides ready-made functions for common math operations.

For example, Math.max(3, 9, 5) returns the largest value; Math.min(3, 9, 5) the smallest. Math.floor(3.7) rounds down, Math.ceil(3.2) rounds up.

Math.round(3.5) rounds to the nearest integer. These functions make number operations easy.

Number conversions

To convert a string to a number, you use the Number(...) function. For example, Number('42') returns the number 42.

If the string does not look like a number, the result is NaN (Not-a-Number). For example, Number('hello') returns NaN.

This is very useful when converting user input to numbers, especially from command-line arguments.

Exercise Find the largest with Math.max

Declare three numbers: a = 12, b = 45, c = 7. Find the largest with Math.max(a, b, c) and print it with console.log.

Show example solution

const a = 12;
const b = 45;
const c = 7;
console.log(Math.max(a, b, c));

Test yourself

Using Math.max

const largest = Math.max(3, ____);

Show answer

const largest = Math.max(3, 9);

Match the Math functions

Math.max

Largest
Math.min

Smallest
Math.floor

Round down
Math.round

Nearest integer
What does Number("42") return?
- The string '42'
- Throws an error
- undefined
- The number 42
Show answer

The number 42 — Number('42') returns the number 42.

Next lesson: Symbol

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