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40 in words

40

forty

40 is written forty.

Ways to write it

As an ordinal: fortieth
Roman numeral: XL
Expanded form: 40

Place value

Place	Digit	Value
tens	4	40
ones	0	0

Number facts

Even or odd: Even
Prime or composite: Composite
Factors: 1, 2, 4, 5, 8, 10, 20 and 40 (8 factors)
First 10 multiples: 40, 80, 120, 160, 200, 240, 280, 320, 360, 400
Square: 40 × 40 = 1,600
Square root: ≈ 6.32
Sum of the digits: 4 + 0 = 4
Rounded to the nearest 10: 40
Number before: 39
Number after: 41
In binary: 101000

Quick check

What number comes just after 40?
Show the answer
41
Is 40 even or odd?
Show the answer
Even
What is 40 + 10?
Show the answer
50

Practise with a game

Count with Me

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Place Value Quest

Ones, tens, hundreds and thousands.

Times Tables Challenge

Practise any times table from 2× to 12×.

Frequently asked questions

How do you write 40 in words?

40 is written "forty".

Is 40 a prime number?

No. 40 is a composite number, because it has more than two factors.

What are the factors of 40?

The factors of 40 are 1, 2, 4, 5, 8, 10, 20 and 40.

How do you write 40 in Roman numerals?

40 in Roman numerals is XL.