49 (number)


49 is the natural number following 48 and preceding 50.

In mathematics

Forty-nine is the square of seven.
It appears in the Padovan sequence, preceded by the terms 21, 28, 37.
Along with the number that immediately derives from it, 77, the only number under 100 not having its home prime known.

Base 10 representation

The sum of the digits of the square of 49 is the square root of 49.
49 is the first square where the digits are squares. In this case 4 and 9 are squares.
Reciprocal
The fraction is a repeating decimal with a period of 42:
There are 42 positive integers that are less than 49 and coprime to 49. Multiplying 020408163265306122448979591836734693877551 by each of these integers results in a cyclic permutation of the original number:
The repeating number can be obtained from 02 and repetition of doubles placed at two places to the right:
02
04
08
16
32
64
128
256
512
1024
2048
+ ...
----------------------
020408163265306122448979591836734693877551...0204081632...

In chemistry

Forty-nine is: