Number reference
49 explained.
49: forty-nine, composite, perfect square; factors, prime factorization, roots, binary, hexadecimal, and digit properties.
Identity and representations
- Written form
- forty-nine
- Classification
- composite
- Factors
- 1, 7, 49
- Prime factorization
- 7 × 7
- Square root
- 7
- Cube root
- 3.659306
- Binary
- 110001
- Octal
- 61
- Hexadecimal
- 31
- Roman numeral
- XLIX
- Digit sum
- 13
- Digital root
- 4
What makes 49 notable
- Perfect square. 49 = 7², so a square of side 7 has an area of 49.
49 in everyday use
Forty-nine is seven weeks in days, the span counted in the Jewish festival calendar between Passover and Shavuot. It is the atomic number of indium, used in touchscreens. The San Francisco 49ers take their name from the prospectors of the 1849 California gold rush. Germany's international dialling code is +49. A 7 × 7 board has 49 squares.
Forty-nine is seven squared and the sum of the first seven odd numbers, 1 + 3 + 5 + 7 + 9 + 11 + 13, a pattern that holds for every square. Its digits, 4 and 9, are themselves both squares, and it is the only two-digit square with that property. In the decimal expansion of 1/49 the digits repeat every 42 places.
Nearby numbers
How to read this page
The factor list shows every way 49 splits into equal whole-number groups — 3 divisors in total. The prime factorisation is the compact form of that same information, and the base conversions restate 49 for contexts that do not use decimal.
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