399 in words
399
three hundred ninety-nine
399 is written three hundred ninety-nine.
Ways to write it
- As an ordinal
- three hundred ninety-ninth
- Roman numeral
- CCCXCIX
- Expanded form
- 300 + 90 + 9
Place value
| Place | Digit | Value |
|---|---|---|
| hundreds | 3 | 300 |
| tens | 9 | 90 |
| ones | 9 | 9 |
Number facts
- Even or odd
- Odd
- Prime or composite
- Composite
- Factors
- 1, 3, 7, 19, 21, 57, 133 and 399 (8 factors)
- First 10 multiples
- 399, 798, 1,197, 1,596, 1,995, 2,394, 2,793, 3,192, 3,591, 3,990
- Square
- 399 × 399 = 159,201
- Square root
- ≈ 19.97
- Sum of the digits
- 3 + 9 + 9 = 21
- Rounded to the nearest 10
- 400
- Rounded to the nearest 100
- 400
- Number before
- 398
- Number after
- 400
- In binary
110001111
Quick check
What number comes just after 399?
Show the answer
400
Is 399 even or odd?
Show the answer
Odd
What is 399 + 10?
Show the answer
409
Practise with a game
Factors, Multiples & Primes
Multiples, factors, prime numbers, square numbers and prime factors.
Roman Numerals
Read and write Roman numerals from I to 3,999.Frequently asked questions
How do you write 399 in words?
399 is written "three hundred ninety-nine".
Is 399 a prime number?
No. 399 is a composite number, because it has more than two factors.
What are the factors of 399?
The factors of 399 are 1, 3, 7, 19, 21, 57, 133 and 399.
How do you write 399 in Roman numerals?
399 in Roman numerals is CCCXCIX.