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Last updated on 22 August 2025

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8421 in Binary

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8421 in binary is written as 1000011110101 because the binary system uses only two digits, 0 and 1, to represent numbers. This number system is used widely in computer systems. In this topic, we are going to learn about binary systems and how to convert 8421 to binary.

8421 in Binary for Indian Students
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8421 in Binary Conversion

The process of converting 8421 from decimal to binary involves dividing the number 8421 by 2. Here, it is divided by 2 because the binary number system uses only 2 digits (0 and 1). The quotient becomes the dividend in the next step, and the process continues until the quotient becomes 0.

 

This is a commonly used method to convert 8421 to binary. In the last step, the remainder is noted down from bottom to top, and that becomes the converted value. For example, the remainders noted down after dividing 8421 by 2 until getting 0 as the quotient is 1000011110101. Remember, the remainders here have been written upside down.

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8421 in Binary Chart

In the table shown below, the first column shows the binary digits (1 and 0) as 1000011110101. The second column represents the place values of each digit, and the third column is the value calculation, where the binary digits are multiplied by their corresponding place values.

 

The results of the third column can be added to cross-check if 1000011110101 in binary is indeed 8421 in the decimal number system.

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How to Write 8421 in Binary

8421 can be converted easily from decimal to binary. The methods mentioned below will help us convert the number. Let’s see how it is done.

 

Expansion Method: Let us see the step-by-step process of converting 8421 using the expansion method.

 

Step 1 - Figure out the place values: In the binary system, each place value is a power of 2. Therefore, in the first step, we will ascertain the powers of 2.

20 = 1

21 = 2

22 = 4

23 = 8

24 = 16

25 = 32

26 = 64

27 = 128

28 = 256

29 = 512

210 = 1024

211 = 2048

212 = 4096

213 = 8192

Since 8192 is less than 8421, we include 213, which is 8192.

 

Step 2 - Identify the largest power of 2: In the previous step, we identified 213 = 8192 as the largest power of 2 less than or equal to 8421. Write 1 in the 213 place and subtract this value from 8421: 8421 - 8192 = 229.

 

Step 3 - Identify the next largest power of 2: Now, find the largest power of 2 that fits into 229, which is 27 = 128. Write 1 in the 27 place. Subtract 128 from the result of the previous step: 229 - 128 = 101.

 

Step 4 - Continue the process: Repeat the process for 101. 26 = 64 fits into 101, so write 1 in the 26 place. 101 - 64 = 37. 25 = 32 fits into 37, so write 1 in the 25 place. 37 - 32 = 5. 22 = 4 fits into 5, so write 1 in the 22 place. 5 - 4 = 1. 20 = 1 fits into 1, so write 1 in the 20 place. 1 - 1 = 0.

 

Step 5 - Identify the unused place values: Fill 0s in the places where no power of 2 was used. Now, by substituting the values, we get: 1 in the 213 place 0 in the 212 place 0 in the 211 place 0 in the 210 place 0 in the 29 place 1 in the 28 place 1 in the 27 place 1 in the 26 place 1 in the 25 place 0 in the 24 place 1 in the 23 place 0 in the 22 place 1 in the 21 place 1 in the 20 place Therefore, 1000011110101 is 8421 in binary.

 

Grouping Method: In this method, we divide the number 8421 by 2. Let us see the step-by-step conversion.

 

Step 1 - Divide 8421 by 2. 8421 / 2 = 4210 remainder 1.

 

Step 2 - Divide the previous quotient (4210) by 2. 4210 / 2 = 2105 remainder 0.

 

Step 3 - Repeat the previous step. 2105 / 2 = 1052 remainder 1.

 

Step 4 - Repeat the previous step. 1052 / 2 = 526 remainder 0.

 

Step 5 - Repeat the previous step. 526 / 2 = 263 remainder 0.

 

Step 6 - Repeat the previous step. 263 / 2 = 131 remainder 1.

 

Step 7 - Repeat the previous step. 131 / 2 = 65 remainder 1.

 

Step 8 - Repeat the previous step. 65 / 2 = 32 remainder 1.

 

Step 9 - Repeat the previous step. 32 / 2 = 16 remainder 0.

 

Step 10 - Repeat the previous step. 16 / 2 = 8 remainder 0.

 

Step 11 - Repeat the previous step. 8 / 2 = 4 remainder 0.

 

Step 12 - Repeat the previous step. 4 / 2 = 2 remainder 0.

 

Step 13 - Repeat the previous step. 2 / 2 = 1 remainder 0.

 

Step 14 - Repeat the previous step. 1 / 2 = 0 remainder 1. Write down the remainders from bottom to top.

 

Therefore, 8421 (decimal) = 1000011110101 (binary).

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Rules for Binary Conversion of 8421

There are certain rules to follow when converting any number to binary. Some of them are mentioned below:

 

Rule 1: Place Value Method

This is one of the most commonly used rules to convert any number to binary. The place value method is the same as the expansion method, where we need to find the largest power of 2. Let’s see a brief step-by-step explanation to understand the first rule. Find the largest power of 2 less than or equal to 8421. Since the answer is 213, write 1 next to this power of 2. Subtract the value (8192) from 8421. So, 8421 - 8192 = 229. Find the largest power of 2 less than or equal to 229. The answer is 27. So, write 1 next to this power. Now, 229 - 128 = 101. Continue the process until you reach 0. Final conversion will be 1000011110101.

 

Rule 2: Division by 2 Method

The division by 2 method is the same as the grouping method. A brief step-by-step explanation is given below for better understanding. First, 8421 is divided by 2 to get 4210 as the quotient and 1 as the remainder. Now, 4210 is divided by 2. Here, we will get 2105 as the quotient and 0 as the remainder. Dividing 2105 by 2, we get 1052 as the quotient and 1 as the remainder. Continue the division process until the quotient becomes 0. Now, write the remainders upside down to get the binary equivalent of 8421, 1000011110101.

 

Rule 3: Representation Method

This rule also involves breaking the number into powers of 2. Identify the powers of 2 and write them down in decreasing order, i.e., 213, 212, 211, etc. Find the largest power that fits into 8421. Repeat the process and allocate 1s and 0s to the suitable powers of 2. Combine the digits (0 and 1) to get the binary result.

 

Rule 4: Limitation Rule

The limitation of the binary system is that only 0s and 1s can be used to represent numbers. The system doesn’t use any other digits other than 0 and 1. This is a base 2 number system, where the binary places represent powers of 2. So, every digit is either a 0 or a 1.

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Tips and Tricks for Binary Numbers till 8421

Learning a few tips and tricks is a great way to solve any mathematical problems easily. Let us take a look at some tips and tricks for binary numbers up to 8421.

 

  • Memorize to speed up conversions: We can memorize the binary forms for numbers 1 to 16 for quick reference.
     
  • Recognize the patterns: There is a peculiar pattern when converting numbers from decimal to binary. 1 → 1 1 + 1 = 2 → 10 2 + 2 = 4 → 100 4 + 4 = 8 → 1000 8 + 8 = 16 → 10000 16 + 16 = 32 → 100000…and so on. This is also called the double and add rule.
     
  • Even and odd rule: Whenever a number is even, its binary form will end in 0. For example, 8421 is odd, and its binary form is 1000011110101, ending in 1. If the number is even, then its binary equivalent will end in 0.
     
  • Cross-verify the answers: Once the conversion is done, we can cross-verify the answers by converting the number back to the decimal form. This will eliminate any unforeseen errors in conversion.
     
  • Practice by using tables: Writing the decimal numbers and their binary equivalents in a table will help us remember the conversions.
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Common Mistakes and How to Avoid Them in 8421 in Binary

Here, let us take a look at some of the most commonly made mistakes while converting numbers to binary.

Mistake 1

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Writing the Remainders From Top to Bottom

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Always remember to read and write the remainders from bottom to top.

 

After converting a number to binary using any of the methods mentioned above, it is important to read the remainders upside down to get the correct value.

Mistake 2

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Misplacing 1s and 0s

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Since the binary system uses only 1s and 0s, we have to be careful while representing any number in its binary form.

 

For example, 8421 can be mistakenly written with the wrong sequence of 1s and 0s.

Mistake 3

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Not Practicing Enough

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Converting numbers from decimal to binary on a regular basis will help boost our confidence and minimize mistakes.

 

Practice daily to become an expert in converting numbers to binary.

Mistake 4

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Adding Instead of Dividing

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When using the grouping method, students may incorrectly add numbers instead of dividing them by 2.

 

Always remember that division is used in the process to convert numbers to binary.

Mistake 5

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Stopping the Division Too Early

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It is important to continue the division process until the quotient becomes 0.

 

Failing to do so will result in errors in the final calculation.

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8421 in Binary Examples

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Problem 1

Convert 8421 from decimal to binary using the place value method.

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1000011110101

Explanation

213 is the largest power of 2, which is less than or equal to 8421.

So place 1 next to 213.

Subtracting 8192 from 8421, we get 229.

The next largest power would be 27.

So place another 1 next to 27.

Continue this process until you reach 0.

By using this method, we can find the binary form of 8421.

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Problem 2

Convert 8421 from decimal to binary using the division by 2 method.

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1000011110101

Explanation

Divide 8421 by 2. In the next step, the quotient becomes the new dividend.

Continue the process until the quotient becomes 0.

Now, write the remainders upside down to get the final result.

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Problem 3

Convert 8421 to binary using the representation method.

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1000011110101

Explanation

Break the number 8421 into powers of 2 and find the largest powers of 2.

We get 213.

So 1 is placed next to 213.

Next, 8421 - 8192 = 229.

Now, the largest power of 2 is 27.

Once again, 1 is placed next to 27.

Continue this process until you reach 0, filling in with zeros for unused powers of 2.

By following this method, we get the binary value of 8421 as 1000011110101.

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Problem 4

How is 8421 written in decimal, octal, and binary form?

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Decimal form - 8421 Octal - 20215 Binary - 1000011110101

Explanation

The decimal system is also called the base 10 system. In this system, 8421 is written as 8421 only.

We have already seen how 8421 is written as 1000011110101 in binary.

So, let us focus on the octal system, which is base 8.

To convert 8421 to octal, we need to divide 8421 by 8 and continue the process.

Write the remainders in reverse order to get 20215 as the octal equivalent of 8421.

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Problem 5

Express 8421 - 7 in binary.

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1000011110100

Explanation

8421 - 7 = 8414

So, we need to write 8414 in binary.

Start by dividing 8414 by 2.

In each step, write down the remainder and continue dividing the quotient by 2 until the quotient becomes 0.

Finally, write down the remainders from bottom to top to get 1000011110100 (binary of 8414).

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FAQs on 8421 in Binary

1.What is 8421 in binary?

1000011110101 is the binary form of 8421.

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2.Where is binary used in the real world?

Computers use binary to store data. Without the binary system, computers wouldn’t be able to process and store information.

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3.What is the difference between binary and decimal numbers?

The binary number system uses only 1s and 0s to represent numbers. The decimal system uses digits from 0 to 9.

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4.Can we do mental conversion of decimal to binary?

Yes. Mental conversion is possible, especially for smaller numbers. Alternatively, we can also memorize the binary forms of smaller numbers.

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5.How to practice conversion regularly?

Practice converting different numbers from decimal to binary. You can also practice converting numbers from other forms, such as octal and hexadecimal, to binary.

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6.How can children in India use numbers in everyday life to understand 8421 in Binary?

Numbers appear everywhere—from counting money to measuring ingredients. Kids in India see how 8421 in Binary helps solve real problems, making numbers meaningful beyond the classroom.

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7.What are some fun ways kids in India can practice 8421 in Binary with numbers?

Games like board games, sports scoring, or even cooking help children in India use numbers naturally. These activities make practicing 8421 in Binary enjoyable and connected to their world.

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8.What role do numbers and 8421 in Binary play in helping children in India develop problem-solving skills?

Working with numbers through 8421 in Binary sharpens reasoning and critical thinking, preparing kids in India for challenges inside and outside the classroom.

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9.How can families in India create number-rich environments to improve 8421 in Binary skills?

Families can include counting chores, measuring recipes, or budgeting allowances, helping children connect numbers and 8421 in Binary with everyday activities.

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Important Glossaries for 8421 in Binary

  • Decimal: It is the base 10 number system, which uses digits from 0 to 9.

 

  • Binary: This number system uses only 0 and 1. It is also called the base 2 number system.

 

  • Place value: Every digit has a value based on its position in a given number. For example, in 102 (base 10), 1 occupies the hundreds place, 0 is in the tens place, and 2 is in the ones place.

 

  • Octal: It is the number system with a base of 8. It uses digits from 0 to 7.

 

  • Quotient: The result obtained by dividing one number by another. In binary conversion, it is important to continue dividing until the quotient is 0.
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Hiralee Lalitkumar Makwana

About the Author

Hiralee Lalitkumar Makwana has almost two years of teaching experience. She is a number ninja as she loves numbers. Her interest in numbers can be seen in the way she cracks math puzzles and hidden patterns.

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Fun Fact

: She loves to read number jokes and games.

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