Decimal to binary number conversion is like translating a number from our everyday counting system (base 10) into the computer’s language (base 2). In binary, you only have two digits (0 and 1), but you can still represent any number using the combination of these two digits. For example, the decimal number 12 becomes 1100 in binary. Just like we learn to say “hello” in different languages, we can also change numbers from one number system to another, such as from decimal to binary or octal (base 8) or hexadecimal (base 16). Once you learn the steps, converting decimal to binary feels simple – and there are online tools to make it even easier. Further, let’s learn more about decimal to binary number conversion!
Table of Contents
It is the process of changing a number from base 10 (decimal) to base 2 (binary). Binary numbers, made of only 0 and 1, are used in computers for coding and processing because computers understand only binary language.
Decimal Number System:
This is the number system we use every day, based on 10 digits (0–9). Each place value is 10 times bigger than the one to its right. Examples: 2130, 2850. If no base is mentioned, we assume it’s decimal.
Binary Number System:
Used mainly in computers, it has only two digits: 0 and 1. Each digit is called a bit. The leftmost bit is the Most Significant Bit (MSB) and the rightmost is the Least Significant Bit (LSB). Examples: 1110, 1001.
The process of converting numbers from one base (such as decimal) to another (such as binary) is known as number system conversion. In computer science, where the binary number system is used to process information, this is particularly crucial.
Here’s how to convert any whole number from decimal to binary:
Divide the decimal number by 2
Record the remainder (0 or 1)
Divide the quotient by 2 again, and record the next remainder
Repeat until the quotient becomes 0
Write the remainders in reverse order - that’s your binary number
Step |
Divide By 2 |
Quotient |
Remainder |
1 |
13 ÷ 2 |
6 |
1 |
2 |
6 ÷ 2 |
3 |
0 |
3 |
3 ÷ 2 |
1 |
1 |
4 |
1 ÷ 2 |
0 |
1 |
Binary = Reverse of remainders = 1101
So, 13 (decimal) = 1101 (binary)
Step |
Divide By 2 |
Quotient |
Remainder |
1 |
45 ÷ 2 |
22 |
1 |
2 |
22 ÷ 2 |
11 |
0 |
3 |
11 ÷ 2 |
5 |
1 |
4 |
5 ÷ 2 |
2 |
1 |
5 |
2 ÷ 2 |
1 |
0 |
6 |
1 ÷ 2 |
0 |
1 |
Binary = 101101
So, 45 (decimal) = 101101 (binary)
Decimal |
Binary |
1 |
1 |
2 |
10 |
3 |
11 |
4 |
100 |
5 |
101 |
6 |
110 |
7 |
111 |
8 |
1000 |
9 |
1001 |
10 |
1010 |
11 |
1011 |
12 |
1100 |
13 |
1101 |
14 |
1110 |
15 |
1111 |
16 |
10000 |
17 |
10001 |
18 |
10010 |
19 |
10011 |
20 |
10100 |
Scenario: Digital Image Storage
Let’s say you take a photo using your smartphone. Each pixel in that photo is stored using numbers, and these numbers represent colors. Suppose one pixel has a grayscale value of 200 in decimal.
To store this information digitally, your phone needs to convert that decimal number (200) into binary, because computers only understand binary (0s and 1s).
Mistake |
Correction Tip |
Forgetting to reverse remainders |
Always write remainders bottom to top |
Stopping before the quotient is 0 |
Continue until the quotient becomes 0 |
Misaligning steps |
Use a clear table for accuracy |
Confusing place values |
Remember: Binary is base-2 |
Below are detailed examples showing how the decimal to binary converter works using the division-by-2 method.
Example 1: Convert 5 to Binary
Step 1: 5 ÷ 2 = 2, remainder = 1
Step 2: 2 ÷ 2 = 1, remainder = 0
Step 3: 1 ÷ 2 = 0, remainder = 1
Binary = 101 (Write remainders in reverse order)
Example 2: Convert 9 to Binary
Step 1: 9 ÷ 2 = 4, remainder = 1
Step 2: 4 ÷ 2 = 2, remainder = 0
Step 3: 2 ÷ 2 = 1, remainder = 0
Step 4: 1 ÷ 2 = 0, remainder = 1
Binary = 1001
Example 3: Convert 25 to Binary
Step 1: 25 ÷ 2 = 12, remainder = 1
Step 2: 12 ÷ 2 = 6, remainder = 0
Step 3: 6 ÷ 2 = 3, remainder = 0
Step 4: 3 ÷ 2 = 1, remainder = 1
Step 5: 1 ÷ 2 = 0, remainder = 1
Binary = 11001
Example 4: Convert 100 to Binary
Step 1: 100 ÷ 2 = 50, remainder = 0
Step 2: 50 ÷ 2 = 25, remainder = 0
Step 3: 25 ÷ 2 = 12, remainder = 1
Step 4: 12 ÷ 2 = 6, remainder = 0
Step 5: 6 ÷ 2 = 3, remainder = 0
Step 6: 3 ÷ 2 = 1, remainder = 1
Step 7: 1 ÷ 2 = 0, remainder = 1
Binary = 1100100
Instructions: Convert each decimal number to its binary equivalent. Show your steps clearly using the division-by-2 method.
Decimal to Binary is a required part to know in maths. Basically, these are two different number systems. Converting decimal numbers to binary is not just a classroom skill - it's a foundational tool in technology and engineering. Number system clears out the computer language problems easily. By learning simple methods and practicing regularly, you’ll master this essential concept with ease. Whether you're preparing for exams, coding in Python, or exploring computer science, this guide will help you every step of the way.
Ans: As computers understand only binary (0s and 1s), so decimal numbers need to be converted for processing and storage.
Ans: Divide repeatedly by 2:
100 ÷ 2 = 50, R = 0
50 ÷ 2 = 25, R = 0
25 ÷ 2 = 12, R = 1
12 ÷ 2 = 6, R = 0
6 ÷ 2 = 3, R = 0
3 ÷ 2 = 1, R = 1
1 ÷ 2 = 0, R = 1
Reverse remainders: 1100100
So, 100 (decimal) = 1100100 (binary)
Ans:
Software Engineering
Data Science
Electronics Engineering
Network Security
Robotics and Automation
Ans: For decimal fractions (like 12.625), convert the integer and fractional parts separately.
12 = 1100
0.625 = (0.101)₂ (multiply by 2 repeatedly)
So, 12.625 = 1100.101
Explore More Number System Conversions with Orchids International School!
CBSE Schools In Popular Cities