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66 in words

66

sixty-six

66 is written sixty-six.

Ways to write it

As an ordinal: sixty-sixth
Roman numeral: LXVI
Expanded form: 60 + 6

Place value

Place	Digit	Value
tens	6	60
ones	6	6

Number facts

Even or odd: Even
Prime or composite: Composite
Factors: 1, 2, 3, 6, 11, 22, 33 and 66 (8 factors)
First 10 multiples: 66, 132, 198, 264, 330, 396, 462, 528, 594, 660
Square: 66 × 66 = 4,356
Square root: ≈ 8.12
Sum of the digits: 6 + 6 = 12
Rounded to the nearest 10: 70
Number before: 65
Number after: 67
In binary: 1000010

Quick check

What number comes just after 66?
Show the answer
67
Is 66 even or odd?
Show the answer
Even
What is 66 + 10?
Show the answer
76

Practise 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

Practise any times table from 2× to 12×.

Frequently asked questions

How do you write 66 in words?

66 is written "sixty-six".

Is 66 a prime number?

No. 66 is a composite number, because it has more than two factors.

What are the factors of 66?

The factors of 66 are 1, 2, 3, 6, 11, 22, 33 and 66.

How do you write 66 in Roman numerals?

66 in Roman numerals is LXVI.