CS 230 - Spring 2020 1-1
Lecture 1 Number Representation CS 230 - Spring 2020 1-1 Number - - PowerPoint PPT Presentation
Lecture 1 Number Representation CS 230 - Spring 2020 1-1 Number - - PowerPoint PPT Presentation
CS 230 Introduction to Computers and Computer Systems Lecture 1 Number Representation CS 230 - Spring 2020 1-1 Number Representation Radix representation radix also know as base Writing natural numbers using a finite alphabet
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Number Representation
Radix representation
radix also know as base
Writing natural numbers using a finite alphabet Given an n-digit number in base r Integer value is
dn− 1dn− 2dn− 3...d3d2d1d0
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Radix Representation
Humans: base-10, decimal
why?
Computers: base-2, binary
why? electrical simplicity
analog/digital conversion (high vs. low voltage)
low-level decimal conversion?
storage expansion / waste
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Examples
Decimal: 13510 Binary: 100112 Hexadecimal: A3216 Septenary: 14407
Use letters starting with A to express digits > 9
5x100 + 3x101 + 1x102 = 13510 1x20 + 1x21 + 0x22 + 0x23 + 1x24 = 1910 2x160 + 3x161 + 10x162 = 261010 0x70 + 4x71 + 4x72 + 1x73 = 56710
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Conversion from Decimal
Repeatedly divide by target base Remainders generate digits
from right to left
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