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45 in words

45

forty-five

45 is written forty-five.

Ways to write it

As an ordinal: forty-fifth
Roman numeral: XLV
Expanded form: 40 + 5

Place value

Place	Digit	Value
tens	4	40
ones	5	5

Number facts

Even or odd: Odd
Prime or composite: Composite
Factors: 1, 3, 5, 9, 15 and 45 (6 factors)
First 10 multiples: 45, 90, 135, 180, 225, 270, 315, 360, 405, 450
Square: 45 × 45 = 2,025
Square root: ≈ 6.71
Sum of the digits: 4 + 5 = 9
Rounded to the nearest 10: 50
Number before: 44
Number after: 46
In binary: 101101

Quick check

What number comes just after 45?
Show the answer
46
Is 45 even or odd?
Show the answer
Odd
What is 45 + 10?
Show the answer
55

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 45 in words?

45 is written "forty-five".

Is 45 a prime number?

No. 45 is a composite number, because it has more than two factors.

What are the factors of 45?

The factors of 45 are 1, 3, 5, 9, 15 and 45.

How do you write 45 in Roman numerals?

45 in Roman numerals is XLV.