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Country and language

Country and language: United Kingdom

Country and language

51 in words

51

fifty-one

51 is written fifty-one.

Ways to write it

As an ordinal
fifty-first
Roman numeral
LI
Expanded form
50 + 1

Place value

PlaceDigitValue
tens550
ones11

Number facts

Even or odd
Odd
Prime or composite
Composite
Factors
1, 3, 17 and 51 (4 factors)
First 10 multiples
51, 102, 153, 204, 255, 306, 357, 408, 459, 510
Square
51 × 51 = 2,601
Square root
≈ 7.14
Sum of the digits
5 + 1 = 6
Rounded to the nearest 10
50
Number before
50
Number after
52
In binary
110011

Quick check

  1. What number comes just after 51?

    Show the answer

    52

  2. Is 51 even or odd?

    Show the answer

    Odd

  3. What is 51 + 10?

    Show the answer

    61

Practise with a game

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Frequently asked questions

How do you write 51 in words?

51 is written "fifty-one".

Is 51 a prime number?

No. 51 is a composite number, because it has more than two factors.

What are the factors of 51?

The factors of 51 are 1, 3, 17 and 51.

How do you write 51 in Roman numerals?

51 in Roman numerals is LI.