Number system  Definition with Examples
The decimal number system consists of 10 digits 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 and is the most commonly used number system. We use the combination of these 10 digits to form all other numbers. The value of a digit in a number depends upon its position in the number. The place value table for the decimal number system is as:
Each place to the left is ten times greater than the place to its right, that is, as we move from the right to the left, the place value increases ten times with each place.
A decimal number system is also called the Base 10 system.
A number 49,365 is read as Fortynine thousand three hundred sixtyfive, where the value of 4 is forty thousand, 9 is nine thousand, 3 is three hundred, 6 is sixty and 5 is five.
In the binary number system, we only use two digits 0 and 1. It means a 2 number system.
Example of binary numbers: 1011; 101010; 1101101
Each digit in a binary number is called a bit. So, a binary number 101 has 3 bits. 499787080
Computers and other digital devices use the binary system. The binary number system uses Base 2.
The word hexadecimal comes from Hexa meaning 6, and decimal meaning 10. So, in a hexadecimal number system, there are 16 digits. It consists of digits 0 to 9 and then has first 5 letters of the alphabet as:
The table below shows numbers 1 to 20 using decimal, binary and hexadecimal numbers.
Decimal 
Binary 
Hexadecimal 
0 
0 
0 
1 
1 
1 
2 
10 
2 
3 
11 
3 
4 
100 
4 
5 
101 
5 
6 
110 
6 
7 
111 
7 
8 
1000 
8 
9 
1001 
9 
10 
1010 
10 
11 
1011 
A 
12 
1100 
B 
13 
1101 
C 
14 
1110 
D 
15 
1111 
E 
16 
10000 
F 
17 
10001 
11 
18 
10010 
12 
19 
10011 
13 
20 
10100 
14 
Fun Facts

The most commonly used number system is the decimal positional numeral system.
Computers use decimal, binary, octal, and hexadecimal number systems.
The hexadecimal number system uses 6 letters (A, B, C, D, E, and F) in addition to 10 digits from 0 to 9.
The base of the hexadecimal number system is 16.