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Last updated on August 20, 2025
345 in binary is written as 101011001 because the binary system uses only two digits, 0 and 1, to represent numbers. This number system is widely used in computer systems. In this topic, we are going to learn about converting 345 to binary.
The process of converting 345 from decimal to binary involves dividing the number 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 345 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 345 by 2 until getting 0 as the quotient is 101011001. Remember, the remainders are written upside down.
In the table shown below, the first column shows the binary digits (1 and 0) as 101011001. 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 101011001 in binary is indeed 345 in the decimal number system.
345 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 345 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
Since 256 is less than 345, we stop at 28 = 256.
Step 2 - Identify the largest power of 2: In the previous step, we stopped at 28 = 256. This is because we have to identify the largest power of 2, which is less than or equal to the given number, 345. Since 28 is the number we are looking for, write 1 in the 28 place. Now the value of 28, which is 256, is subtracted from 345. 345 - 256 = 89
Step 3 - Identify the next largest power of 2: In this step, we need to find the largest power of 2 that fits into the result of the previous step, 89. So, the next largest power of 2 is 26, which is 64. Write 1 in the 26 place. And then subtract 64 from 89. 89 - 64 = 25
Step 4 - Continue with remaining powers of 2: Repeat the process with the remaining number 25. The largest power of 2 less than or equal to 25 is 24, which is 16. Write 1 in the 24 place and subtract 16 from 25. 25 - 16 = 9
Step 5 - Repeat the process for 9: The largest power of 2 less than or equal to 9 is 23, which is 8. Write 1 in the 23 place and subtract 8 from 9. 9 - 8 = 1
Step 6 - Final step for 1: The largest power of 2 that fits into 1 is 20, which is 1. Write 1 in the 20 place and subtract 1 from 1. 1 - 1 = 0
Step 7 - Fill remaining places with 0: In the remaining places, write 0s. Now, by substituting the values, we get: 0 in the 21 place 0 in the 22 place 0 in the 25 place 0 in the 27 place
Step 8 - Write the values in reverse order: We now write the numbers upside down to represent 345 in binary. Therefore, 101011001 is 345 in binary.
Grouping Method: In this method, we divide the number 345 by 2. Let us see the step-by-step conversion.
Step 1 - Divide the given number 345 by 2. 345 / 2 = 172. Here, 172 is the quotient and 1 is the remainder.
Step 2 - Divide the previous quotient (172) by 2. 172 / 2 = 86. Here, the quotient is 86 and the remainder is 0.
Step 3 - Repeat the previous step. 86 / 2 = 43. Now, the quotient is 43, and 0 is the remainder.
Step 4 - Continue dividing. 43 / 2 = 21. The quotient is 21 and the remainder is 1.
Step 5 - Continue dividing. 21 / 2 = 10. The quotient is 10 and the remainder is 1.
Step 6 - Continue dividing. 10 / 2 = 5. The quotient is 5 and the remainder is 0.
Step 7 - Continue dividing. 5 / 2 = 2. The quotient is 2 and the remainder is 1.
Step 8 - Continue dividing. 2 / 2 = 1. The quotient is 1 and the remainder is 0.
Step 9 - Final division. 1 / 2 = 0. The remainder is 1. We stop the division here because the quotient is 0.
Step 10 - Write down the remainders from bottom to top. Therefore, 345 (decimal) = 101011001 (binary).
There are certain rules to follow when converting any number to binary. Some of them are mentioned below:
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 345. Since the answer is 28, write 1 next to this power of 2. Subtract the value (256) from 345. So, 345 - 256 = 89. Find the largest power of 2 less than or equal to 89. The answer is 26. So, write 1 next to this power. Now, 89 - 64 = 25. Continue until the remainder is 0. Final conversion will be 101011001.
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, 345 is divided by 2 to get 172 as the quotient and 1 as the remainder. Now, 172 is divided by 2. Here, we will get 86 as the quotient and 0 as the remainder. Dividing 86 by 2, we get 0 as the remainder and 43 as the quotient. Continue until the quotient becomes 0. Now, we write the remainders upside down to get the binary equivalent of 345, 101011001.
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., 28, 27, 26, 25, 24, 23, 22, 21, and 20. Find the largest power that fits into 345. 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.
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. To convert 345, we use 1s for 28, 26, 24, 23, 20 and 0s for 27, 25, 22, 21.
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 345.
Here, let us take a look at some of the most commonly made mistakes while converting numbers to binary.
Convert 345 from decimal to binary using the place value method.
101011001
28 is the largest power of 2, which is less than or equal to 345.
So place 1 next to 28.
Subtracting 256 from 345, we get 89.
So the next largest power would be 26.
So place another 1 next to 26.
Now, subtracting 64 from 89, we get 25.
Repeat the process until the remainder is 0.
By using this method, we can find the binary form of 345.
Convert 345 from decimal to binary using the division by 2 method.
101011001
Divide 345 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.
Convert 345 to binary using the representation method.
101011001
Break the number 345 into powers of 2 and find the largest powers of 2.
We get 28. So 1 is placed next to 28. Next, 345 - 256 = 89.
Now, the largest power of 2 is 26.
Once again, 1 is placed next to 26.
Continue the process until the remainder is 0.
By following this method, we get the binary value of 345 as 101011001.
How is 345 written in decimal, octal, and binary form?
Decimal form - 345 Octal - 531 Binary - 101011001
The decimal system is also called the base 10 system. In this system, 345 is written as 345 only.
We have already seen how 345 is written as 101011001 in binary.
So, let us focus on the octal system, which is base 8.
To convert 345 to octal, we need to divide 345 by 8.
So 345 / 8 = 43 with 1 as the remainder.
In the next step, divide the quotient from the previous step (43) by 8.
So 43 / 8 = 5 with 3 as the remainder.
Then divide 5 by 8, which results in 0 with 5 as the remainder.
The division process stops here because the quotient is now 0.
Here, 1, 3, and 5 are the remainders, and they have to be written in reverse order.
So, 531 is the octal equivalent of 345.
Express 345 - 100 in binary.
111101
345 - 100 = 245
So, we need to write 245 in binary.
Start by dividing 245 by 2.
We get 122 as the quotient and 1 as the remainder.
Next, divide 122 by 2.
Now we get 61 as the quotient and 0 as the remainder.
Continue dividing until the quotient becomes 0.
Now write the remainders from bottom to top to get 111101 (binary of 245).
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.
: She loves to read number jokes and games.