Number System
The technique to represent and work with numbers in computer is called number system. In computer, there are few types of number system used like Binary number, Decimal number, octal number, hexadecimal number system. In these decimal number system is the most common number system. We use decimal number system in our day to day life whereas, a computer convert all kind of data and information in binary number system. The total number of digits used in a number system is called its Base or Radix.
Decimal Number System :-
Decimal number system is a base 10 number system having 10
digits from 0 to 9. This means that any numerical quantity can be represented
using these 10 digit digits. Digital number system is is also a positional
value system. This means that the value of digits will depend upon its position
for example :- 734, 971 and 207. In these three numbers the value of 7 is
different.
1)
In 734, the value of 7 is 700 or 7 into hundred
or 7*102 .
2)
In 971, the value of 7 is 70 or 7*10 or 7*101.
3)
In 207, the value of 7 is 7 units or 7 or 7*1 or
7 * 100
The weighted of each position can be
represented as follows
|
105 |
104 |
103 |
102 |
101 |
100 |
In distance systems, instruction are given
through electric signals and variation is done by wearing the voltage of the
signal. Having 10 different voltage to implement decimal number system in
digital equipment is difficult. So many number system that are easier to
implement digitally have been developed. Let’s have a look in detail.
Binary Number System:-
Each band in digits is also called a bit. Bani number system is also potential value system where each digit has a value expressed in the power of 2 as follows.
|
25 |
24 |
23 |
22 |
21 |
20 |
MSB LSB And decimal equivalence of this number is
the sum of product of each digit with its potential value, 110102 = 1 * 24 + 1* 23 +
1 * 22 + 1 * 21 +
1 * 20 Octal Number System:- Octal number systems has eight digit 0,1,2,3,4,5,6 and 7. Octal
number system is also a positional value system, where each digit has its value
expressed in the powers of 8. As given
Decimal equivalence of any octal number is sum of product of
each digit with its potential value.
3458 = 3 *82 +
4 * 81 + 5 * 80 = 3 * 64 + 4 * 8 + 5 *1 = 192 + 32 +5
Hexadecimal Number System:- Hexadecimal number system has 16 symbols - 0 to 9 and A to where E is equal to 10B is equal to eleven and so on till F please stop hexadecimal number system is also a potential value system with where each digit has its value expressed in the power of 16 as given
Decimal equivalence of any hexadecimal number is sum of product of each digit with its potential value. 18AD16 = 1 *163 + 8 *162 + A *161
+ D*160 Where A is equal to 10 and D is
equal to 13 = 1 * 4096 + 8 * 256
+ 10 * 16 + 13*1 = 4096 + 2048 + 160
+ 13 = 6317
Conversion of decimal number to other number system 1) 1) Convert decimal number to binary number
system :- Decimal number can be converted to by repeated division of
the number by two while recording the remainder. for example :- = 43 / 2 = 21 quotient and remainder is 1 = 21/ 2 = 10 quotient and remainder is 1 = 10/2 = 5 quotient and remainder is 0 = 5/2 = 2 quotient and remainder is 1 = 2/2 = 1 quotient and remainder is 0 Now the reminders are to be read read from bottom to top to obtain the equivalent. 4310 = 1010112 1) 2) Convert decimal number to octal number system:-
Decimal number can be converted to octal by
repeated division of the number by 8 while recording the remainders. for example:- =843 / 8 = 105 quotient and remainder is 3 = 105/ 8 = 13 quotient and remainder is 1 = 13/8 = 1 quotient and remainder is 5 Now the reminders are to be read read from bottom to top to obtain the equivalent. 84310 = 5138 Conversion of binary number to other number system1) Convert binary number to Octal number system :- Let's use the example from the image: Binary number: 110101101.01101₂ Step 1: Divide the binary digits into groups of 3Start grouping from the binary point. For the whole-number part, move from right to left: 110 101 101 For the fractional part, move from left to right: 011 010 So we get: 110 101 101 . 011 010
Step 2: Convert each group of 3 bitsUse this simple table:
Now convert: 110 → 6 101 → 5 101 → 5 After the decimal point: 011 → 3 010 → 2 Therefore: 110 101 101 . 011 010 becomes 6 5 5 . 3 2 Final answer:(110101101.01101)₂ = (655.32)₈ Easy rule to remember:Binary → Octal → Groups of 3 110 | 101 | 101 . 011 | 010 ↓ ↓ ↓ ↓ ↓ 6 5 5 3 2 Answer = 655.32₈ 2) Convert binary number to decimal number system :- Step-by-Step Method
The easiest rule is:
Convert |
| Binary | Hexadecimal |
|---|---|
| 0000 | 0 |
| 0001 | 1 |
| 0010 | 2 |
| 0011 | 3 |
| 0100 | 4 |
| 0101 | 5 |
| 0110 | 6 |
| 0111 | 7 |
| 1000 | 8 |
| 1001 | 9 |
| 1010 | A |
| 1011 | B |
| 1100 | C |
| 1101 | D |
| 1110 | E |
| 1111 | F |
Now convert each group:
0001 → 1
0110 → 6
1110 → E
1101 → D
So:
0001 | 0110 | 1110 | 1101
becomes:
1 | 6 | E | D
Final answer:
(1011011101101)₂ = (16ED)₁₆
Why do we use 3 and 4?
This is the most important concept for students.
Binary → Octal
Octal has 8 possible values:
0, 1, 2, 3, 4, 5, 6, 7
And:
2³ = 8
Therefore:
3 binary bits = 1 octal digit
Example:
101₂ = 5₈
Binary → Hexadecimal
Hexadecimal has 16 possible values:
0–9, A, B, C, D, E, F
And:
2⁴ = 16
Therefore:
4 binary bits = 1 hexadecimal digit
Example:
1101₂ = D₁₆
🧠 Super-Easy Memory Trick
Tell students to remember this:
OCTAL = 3
Octal → 3 bits
HEXA = 4
Hexadecimal → 4 bits
So:
BINARY │ ┌───────┴────────┐ ↓ ↓ OCTAL HEXADECIMAL │ │ Groups of 3 Groups of 4 │ │ ↓ ↓ 0 – 7 0 – 9, A – F
One Important Difference
For octal, students only need to remember:
000–111 → 0–7
For hexadecimal, after 9 we use letters:
10 = A 11 = B 12 = C 13 = D 14 = E 15 = F
So students should not get confused when they see letters in a hexadecimal answer.
For example:
1010₂ = 10₁₀ = A₁₆
and
1111₂ = 15₁₀ = F₁₆
🔥 Compare All Three Methods
| Conversion | What to do |
|---|---|
| Binary → Decimal | Use powers of 2 and add |
| Binary → Octal | Group binary digits in 3s |
| Binary → Hexadecimal | Group binary digits in 4s |
Final shortcut
| Conversion | Group binary into | Example |
|---|---|---|
| Binary → Octal | 3 bits | 101 → 5 |
| Binary → Hexadecimal | 4 bits | 1101 → D |
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