We work with numbers using base 10 or the decimal system. When we have a number such as
245
This is interpreted as :
2 * 10 to power 2 + 4 * 10 to power 1 + 5
If we have a base such as 10 then the digits range from 0 to 9 ( 0 to base -1 ) . When we go from right to left we
multiply the digit by the base to the power increasing the power by 1 each time.
Computer work with base 2 also called the binary system. The digits are 0 and 1 . The number
101
is 5 in decimal system( 1*2 power2 + 0 + 1 ) .
If we have 3 digits then the unsigned number will look like below:
000 -- 0
001 -- 1
010 -- 2
011 -- 3
100 -- 4
101 -- 5
110 -- 6
111 -- 7
Two's complement.
A negative binary number is represented in two's complement. In this scheme the leftmost bit is "1" and represents the negative number. The right most bits are inverted and then a "1" is added to get the negative number amount.
Ex:
101
The bit "01" are inverted to form "10" and then a "1" is added to form "11" so the number "101" is actually "-3" . If we have 3 digits then the signed numbers look as below:
000 0
001 1
010 2
011 3
100 -4
101 -3
110 -2
111 -1
Base 16 also called Hexadecimal system . The digits are 0-9, A-F with A representing 10 and F representing 15.
Examples:
F0 - 240
AF - 175
The computer stores numbers in binary. The smallest unit is called 1 bit that can be 0 or 1 .
1 Byte = 8 Bits
1 Kb = 1,024 Bytes
1 Mb = 1,024 Kb
1 Gb = 1,024 Mb