142857, the six repeating digits of 1/7, 0.142857, is the best-known cyclic number in base 10. If it is multiplied by 2, 3, 4, 5, or 6, the answer will be a cyclic permutation of itself, and will correspond to the repeating digits of 2/7, 3/7, 4/7, 5/7, or 6/7 respectively.
142,857 is a Kaprekar number and a Harshad number (in base 10).
- "142857" | 2015-08-05 | 100 Upvotes 22 Comments
An illegal number is a number that represents information which is illegal to possess, utter, propagate, or otherwise transmit in some legal jurisdiction. Any piece of digital information is representable as a number; consequently, if communicating a specific set of information is illegal in some way, then the number may be illegal as well.
- "Illegal number – Represents information which is illegal to possess" | 2021-06-16 | 39 Upvotes 26 Comments
- "Illegal number" | 2019-01-11 | 6 Upvotes 10 Comments
- "Illegal number - Wikipedia" | 2013-10-01 | 14 Upvotes 1 Comments
- "Illegal Numbers" | 2012-10-28 | 184 Upvotes 95 Comments
The long and short scales are two of several naming systems for integer powers of ten which use some of the same terms for different magnitudes.
For whole numbers smaller than 1,000,000,000 (109), such as one thousand or one million, the two scales are identical. For larger numbers, starting with 109, the two systems differ. For identical names, the long scale proceeds by powers of one million, whereas the short scale proceeds by powers of one thousand. For example, one billion is one thousand millions in the short scale, while it is one million millions in the long scale. The long scale system introduces new terms for the intervening values, typically replacing the word ending -ion with -iard.
- "Long and short scales" | 2015-07-27 | 18 Upvotes 4 Comments
In number theory, a narcissistic number (also known as a pluperfect digital invariant (PPDI), an Armstrong number (after Michael F. Armstrong) or a plus perfect number) in a given number base is a number that is the sum of its own digits each raised to the power of the number of digits.
- "Narcissistic Number" | 2015-09-07 | 27 Upvotes 2 Comments
The yottabyte is a multiple of the unit byte for digital information. The prefix yotta indicates multiplication by the eighth power of 1000 or 1024 in the International System of Units (SI), and therefore one yottabyte is one septillion (one long scale quadrillion) bytes. The unit symbol for the yottabyte is YB. The yottabyte, adopted in 1991, is the largest of the formally defined multiples of the byte.
- 1 YB = 10008bytes = 1024bytes = 1000000000000000000000000bytes = 1000zettabytes = 1trillionterabytes
A related unit, the yobibyte (YiB), using a binary prefix, is equal to 10248bytes (approximately 1.209 YB).
- "Yottabyte" | 2013-06-10 | 53 Upvotes 40 Comments
Kaktovik Iñupiaq numerals are a featural positional numeral system created by Alaskan Iñupiat.
Arabic numeral notation, which was designed for a base-10 numeral system, is inadequate for the Inuit languages, which use a base-20 numeral system. Students from Kaktovik, Alaska invented a base-20 numeral notation in 1994 to rectify this issue, and this system spread among the Alaskan Iñupiat and has been considered in other countries where Inuit languages are spoken.
The image at right shows the digits 0 to 19. Twenty is written as a one and a zero (I0), forty as a two and a zero (V0), four hundred as a one and two zeros (I00), eight hundred as a two and two zeros (V00), etc.
- "Kaktovik Iñupiaq Numerals" | 2020-12-07 | 26 Upvotes 11 Comments
The long hundred, also known as the great hundred or twelfty, is the number that was referred to as "hundred" in Germanic languages prior to the 15th century, which is now known as 120, one hundred and twenty, or six score. The number was simply described as hundred and translated into Latin in Germanic-speaking countries as centum (Roman numeral C), but the qualifier "long" is now added because present English uses the word "hundred" exclusively to refer to the number of five score (100) instead.
The long hundred was 120 but the long thousand was reckoned decimally as 10 long hundreds (1200).
- "Long Hundred" | 2021-02-08 | 97 Upvotes 106 Comments
Kaktovik numerals are a featural positional numeral system created by Alaskan Iñupiat.
Arabic numeral notation, which was designed for a base-10 numeral system, is inadequate for the Inuit languages, which use a base-20 numeral system. Students in Kaktovik, Alaska, invented a base-20 numeral notation in 1994 to rectify this issue, and this system spread among the Alaskan Iñupiat and has been considered in other countries where Inuit languages are spoken.
The image at right shows the digits 0 to 19. Twenty is written as a one and a zero (\ɤ), forty as a two and a zero (Vɤ), four hundred as a one and two zeros (\ɤɤ), eight hundred as a two and two zeros (Vɤɤ), etc.
- "Kaktovik numerals – A base-20 number system that is visually easy too" | 2021-03-04 | 39 Upvotes 2 Comments