Decimal is a term that describes the base-10 number system, probably the most commonly used number system. The decimal number system consists of ten single- digit numbers: 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. The number after 9 is 10. The number after 19 is 20 and so forth. Additional powers of 10 require the addition of another positional digit.

In computing, the binary , octal , or hexadecimal number system may be used instead of the decimal system. All these schemes have a number of digits that is a power of 2. This is an advantage in systems that use high and low digital states.

Decimal |
Binary |
Octal |
Hexadecimal |
---|---|---|---|

1 | 1 | 1 | 1 |

2 | 10 | 2 | 2 |

3 | 11 | 3 | 3 |

4 | 100 | 4 | 4 |

5 | 101 | 5 | 5 |

6 | 110 | 6 | 6 |

7 | 111 | 7 | 7 |

8 | 1000 | 10 | 8 |

9 | 1001 | 11 | 9 |

10 | 1010 | 12 | A |

11 | 1011 | 13 | B |

12 | 1100 | 14 | C |

13 | 1101 | 15 | D |

14 | 1110 | 16 | E |

15 | 1111 | 17 | F |

16 | 10000 | 20 | 10 |

17 | 10001 | 21 | 11 |

etc | etc | etc | etc |