COMPSCI 105 Lecture Notes - Lecture 2: File System Permissions, Dna, Binary Number
28 Oct 2014
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Document Summary
Labels for numbers using different sets of symbols. We use base 10 (decimal) but it isn"t special. Used in le permissions on web servers (linux) Uses the positional notation developed by arab and hindu mathematicians of a thousand years ago. Requires the invention of zero to work (so that 12, 120, 102, 10. 2, 100. 02 are all distinct) Any number to the 0th power is 1. Base (radix): number of distinct symbols used for counting. Exponents: powers of the base for each digit. Increase linearly going to the left, decrease to the right; determines the weight/contribution of each digit. Coef cients: digits of the number; range is always from 0 to base-1. Changing a base changes only the labeling of a number, not its value. Sumerians & babylonians used base 60 (used in clocks and angle measures) Only 4 symbols used for counting: 0, 1, 2, 3. Only 2 symbols are used for counting: 0, 1.
