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There are four types of number systems, which are as follows:
1. Decimal number system 2. Binary number system
3. Octal number system 4. Hexadecimal number system
The decimal number system is used in general. However, computers use a binary number system.
The octal and hexadecimal number systems are also used on the computer.
Decimal Number System
A number system made up of 10 digits from 0 to 9, is known as decimal number system. The
base of the decimal number system is 10. It is also known as the base-10 system.
In the decimal number system, the position of the first digit towards the left side of the decimal
point is 0. The position of the second digit towards the left side of the decimal point is 1. Similarly,
the position of the first digit towards the right side of the decimal point is –1. The position of the
second digit towards the right side of the decimal point is –2, and so on.
In simple words, the successive position to the left of the decimal point represents units, tens,
hundreds, thousands, and so on.
The value of a number is determined by multiplying the digits with the weight of their position
and adding the results. This method is known as the expansion method. The right-most digit of
the number has the lowest weight. This digit is called Least Significant Digit (LSD). The left-most
digit of a number has the highest weight. This digit is called the Most Significant Digit (MSD).
The digit 7 in the number 724 is the most significant digit and 4 is the least significant digit.
The table shows the positional weight of decimal number (724) .
10
Hundereds Tens Units
Weights 10 2 10 1 10 0
Real Value of each digit 7 × 10 2 2 × 10 1 4 × 10 0
Result 700 20 4
For Example: (3698)
10 Info Byte
0
8 signifies 8 x 10 = 8
A single binary digit (like '0' or ‘1’) is called a ‘bit’. For
1
9 signifies 9 x 10 = 90
example, 11010 is five bits long. The word 'bit' is made
2
6 signifies 6 x 10 = 600 from the words 'binary' and 'digit'.
3
3 signifies 3 x 10 = 3000
Upon adding them = 3000 + 600 + 90 + 8 = 3698
Binary Number System
A number system made up of only two digits: 0 and 1, is known as the binary number system.
When the binary number system is used, every number is formed using only 0 and 1. The word
binary comes from ‘Bi’ meaning two that’s why the base of the binary number is 2. It is also
known as the base-2 system.
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