FANDOM

10,405 Pages

2 (two) is a positive integer following 1 and preceding 3. Its ordinal form is written "second" or "2nd".

Properties

2 is even, and a prime number — the only number with both of those properties. (An old joke states that this makes 2 the oddest prime of all.)

Since 10 is a multiple of 2, a number written in base 10 can be easily be tested for evenness by looking at the last decimal digit. Even numbers always end in 0, 2, 4, 6, or 8.

2 is the smallest superperfect number.

Base two, binary, is used as the basis of modern computing.

In googology

Calling any standard hyperoperation (addition, multiplication, exponentiation, tetration, etc.) with 2 as both of its arguments will always result in 4. BEAF arrays using 2 as a base tend to become degenerate and evaluate to 4: {2, 2 (1) 2} = {2, 2} = 22 = 4. For this reason, Bowers often coins googologisms based on the number 3, which do not become degenerate.

In Greek-based number naming systems, 2 is associated with prefix di-, and with prefix duo- in Latin systems.

2 can be named boogaone with the booga- prefix, since booga(1) = 1 + 1 = 2.

Using Sbiis Saibian's naming system, this number is called clover mite-crumb.[1]

Aarex Tiaokhiao coined the name binary-uoonol for this number.[2]

Username5243 coined the name Binary-Goonol for this number, and it's equal to 2[1]1 in Username5243's Array Notation.[3]

As a cash denomination

Some currencies, such as the Ghanaian cedi and the United States dollar, have banknotes with this number in the denomination.

Some currencies, such as the euro and the pound sterling, have coins with this number in the denomination.

Sources

-minutia group
n-ary numbers with multipliers
Eyelash mite group: eyelash mite-speck · eyelash mite-crumb · eyelash mite-chunk · (binary/ternary/octal)eyelash mite · eyelash mite-bunch · eyelash mite-crowd · eyelash mite-swarm
Dust mite group: dust mite-speck · dust mite-crumb · dust mite-chunk · (binary/ternary/octal)dust mite · dust mite-bunch · dust mite-crowd · dust mite-swarm
Cheese mite group: cheese mite-speck · cheese mite-crumb · cheese mite-chunk · (binary/ternary/octal)cheese mite · cheese mite-bunch · cheese mite-crowd · cheese mite-swarm
Clover mite group: clover mite-speck · clover mite-crumb · clover mite-chunk · (binary/ternary/octal)clover mite · clover mite-bunch · clover mite-crowd · clover mite-swarm
Pipsqueak group: (binary/ternary/octal)pipsqueak
Little squeaker group: (binary/ternary/octal)little squeaker
Small fry group: (binary/ternary/octal)small fry
Guppy group: (binary/ternary/octal)guppyspeck · (binary/ternary/octal)guppycrumb · (binary/ternary/octal)guppychunk · (ternary/quaternary/quinary/duodecimal/hexadecimal/vigesimal/sexagesimal)guppy(bit/byte)
Minnow group: (binary/ternary/octal)minnowspeck · (binary/ternary/octal)minnowcrumb · (binary/ternary/octal)minnowchunk · (ternary)minnow(bit/byte)
Goby group: (binary/ternary/octal)gobyspeck · (binary/ternary/octal)gobycrumb · (binary/ternary/octal)gobychunk · (ternary)goby(bit/byte)