Twenty eight
| Twenty eight | |
|---|---|
| 28 | |
| presentation | |
| Roman | XXVIII |
| dual | 1 1100 |
| Octal | 34 |
| Duodecimal | 24 |
| Hexadecimal | 1C |
| Morse code | · · - - - - - - · · |
| Mathematical properties | |
| sign | positive |
| parity | straight |
| Factorization | |
| Divider | 1, 2, 4, 7, 14, 28 |
The twenty-eight (28) is the natural number between twenty-seven and twenty-nine . She is straight .
mathematics
- 28 is the second and only two-digit perfect number since it is the sum of its positive real factors.
- It is a triangular number and the sum of the first 5 prime numbers .
- 28 is the smallest natural number of four in two different ways as the sum of squares can be written .
Natural sciences
- In the periodic table of the elements, 28 is the atomic number of nickel .
- In nuclear physics , 28 is a magic number .
- The apparent period of rotation of the sun as seen from the earth is about 28 days.
- 28 days is the average length of a menstrual cycle .
Others
- The February has the Gregorian calendar 28 days (except in leap years ). The Gregorian calendar repeats itself after a period of 28 years , to every 100 years. This means that the days up to 2100 always fall on the same day of the week in a 28-year rhythm.
- There are 28 letters in the Danish , Swedish , Arabic and Esperanto alphabet .
- The adult human being has 28 teeth without wisdom teeth .
- Six dominoes contain 28 game pieces.
- Among right-wing extremists, 28 is a code number for Blood and Honor (B and H are the 2nd and 8th letters of the alphabet).
- According to Jewish tradition, the sun follows a cycle of 28 years in which it returns once to its place in creation . Therefore, the blessing of Birkat ha-Chama is recited every 28 years in April .
- There are 28 residences in Chinese astronomy that are equivalent to the 12 zodiac signs of the western world.