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15 in words

15

fifteen

15 is written fifteen.

Ways to write it

As an ordinal: fifteenth
Roman numeral: XV
Expanded form: 10 + 5

Place value

Place	Digit	Value
tens	1	10
ones	5	5

Number facts

Even or odd: Odd
Prime or composite: Composite
Factors: 1, 3, 5 and 15 (4 factors)
First 10 multiples: 15, 30, 45, 60, 75, 90, 105, 120, 135, 150
Square: 15 × 15 = 225
Square root: ≈ 3.87
Sum of the digits: 1 + 5 = 6
Rounded to the nearest 10: 20
Number before: 14
Number after: 16
In binary: 1111

Quick check

What number comes just after 15?
Show the answer
16
Is 15 even or odd?
Show the answer
Odd
What is 15 + 10?
Show the answer
25

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 15 in words?

15 is written "fifteen".

Is 15 a prime number?

No. 15 is a composite number, because it has more than two factors.

What are the factors of 15?

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

How do you write 15 in Roman numerals?

15 in Roman numerals is XV.