35_lesson.txt

Today is Wednesday on September 27th

lesson 35 page 53

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17. Computer Fundamental -- Number System

When we type some letters or words, the computer translates them into numbers as computers can understand only numbers. A computer can understand the positional number system where type they are only a few symbols called digits and these symbols represent different values depending on the position they occupy in the number.
The value of each digit in a number can be determined using:
    the digit
    the position of the digit in the number
    the base of the number system (where the base is defined as the total number of digits available in the number system)

Decimal Number System
The number system that we use in our day-to-day life is the decimal number system. Decimal number system has base 10 as it uses 10 digits from 0 to 9. In decimal number system, the successive positions to the left of the decimal point represent: units, tens, hundreds, thousands, and so on.
Each position represents a specific power of the base (10), For example, the decimal number 1234 consists of the digit 4 in the units position, 3 in the tens position, 2 in the hundreds position and 1 in the thousands position. Its value can be written as:

( 1 x 1000  ) + ( 2 x 100 ) + ( 3 x 10 ) + ( 4 x 1 )
( 1 x 103 ) + ( 2 x 102 ) + ( 3 x 101 ) + ( 4 x 100 )
1000 + 200 + 30 + 4
1234

As a computer programmer or an IT professional, you should understand the following number systems which are frequently used in computers.
1.   Binary Number System      Base 2. Digits used: 0, 1
2.   Octal Number System       Base 8. Digits used: 0 to 7
3.   Hexadecimal Number System Base 16. Digits used: 0 to 9 and A to F

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