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18 in words

18

eighteen

18 is written eighteen.

Ways to write it

As an ordinal: eighteenth
Roman numeral: XVIII
Expanded form: 10 + 8

Place value

Place	Digit	Value
tens	1	10
ones	8	8

Number facts

Even or odd: Even
Prime or composite: Composite
Factors: 1, 2, 3, 6, 9 and 18 (6 factors)
First 10 multiples: 18, 36, 54, 72, 90, 108, 126, 144, 162, 180
Square: 18 × 18 = 324
Square root: ≈ 4.24
Sum of the digits: 1 + 8 = 9
Rounded to the nearest 10: 20
Number before: 17
Number after: 19
In binary: 10010

Quick check

What number comes just after 18?
Show the answer
19
Is 18 even or odd?
Show the answer
Even
What is 18 + 10?
Show the answer
28

Practice with a game

Count with Me

Count pictures up to 5, 10 or 20 and compare groups.

Place Value Quest

Ones, tens, hundreds and thousands.

Times Tables Challenge

Practice any times table from 2× to 12×.

Frequently asked questions

How do you write 18 in words?

18 is written "eighteen".

Is 18 a prime number?

No. 18 is a composite number, because it has more than two factors.

What are the factors of 18?

The factors of 18 are 1, 2, 3, 6, 9 and 18.

How do you write 18 in Roman numerals?

18 in Roman numerals is XVIII.