Number System

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# Number System - PowerPoint PPT Presentation

Number System. What’s the most natural way to count?. Number System. What’s the most natural way to count? Use your hands. ( or maybe feet too! ). Number System. In ancient times, people use notches What’s the problem?. Number System.

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## PowerPoint Slideshow about 'Number System' - miracle

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Presentation Transcript
Number System
• What’s the most natural way to count?
Number System
• What’s the most natural way to count?Use your hands. ( or maybe feet too! )
Number System

In ancient times, people use notches

What’s the problem?

Number System
• The need for a number system to count. -- a small set of symbols-- has to be convenient for calculation-- has to cover all the numbers, of course…
• What are some of the number systems that we are using?
Number System
• Decimal numbers
• Money!
• Roman numerals.

Why decimals?

Number System
• Roman NumeralsI (1), II ( 2 ), III ( 3) What is 4 ?
Number System
• IV ( 4 )
• V ( 5 ), VI ( 6 ) … IX( 9 ), X( 10 ), XI ( 11 ) …L ( 50 ), C ( 100 ) , D ( 500 )
Number System
• How good is it?
Number System
• CDXLVIII is 448
Number System
• 600 AD: The Arabic number system is started. In 15th Century, it is prevalent in Europe.So the Arabic decimal number system is great for us. But is it good for every body?
Number System
• What’s a decimal system? What’s base-10?
• Really, 657 = 6 * 100 + 5 * 10 + 7 * 1 = 6 * 102 + 5 * 101 + 7 * 100
Number System
• So what base would E.T. use?
Number System
• 657 ( in E.T.’s system) = 6 * 82 + 5 * 81 + 7 * 80 = ? ( in decimal )
Number System
• 657( Octal ) = 431 ( in decimal )What about computer? Which base would it like to use?
Number System
• 1011 = 1 * 23 + 0 * 22 + 1 * 21 + 1 * 20

=11 ( in decimal )

Number System
• To do addition in binary 1011 + 1010 10101
Number System

What else can we do with numbers other than counting and arithmetic?

Number System
• We can encode any symbols with numbers!!Hence, a computer can store all kinds of stuff by representing symbols as binary numbers.