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Last updated on 17 August 2025
625 in binary is written as 1001110001 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 625 in the binary system.
The process of converting 625 from decimal to binary involves dividing the number 625 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 625 to binary. In the last step, the remainder is noted down bottom side up, and that becomes the converted value.
For example, the remainders noted down after dividing 625 by 2 until getting 0 as the quotient form the binary number 1001110001. Remember, the remainders here have been written upside down.
In the table shown below, the first column shows the binary digits (1 and 0) as 1001110001.
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 1001110001 in binary is indeed 625 in the decimal number system.
625 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 625 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
Since 512 is the largest power of 2 less than 625, we stop at 2^9 = 512.
Step 2 - Identify the largest power of 2: In the previous step, we stopped at 2^9 = 512. This is because in this step, we have to identify the largest power of 2, which is less than or equal to the given number, 625. Since 29 is the number we are looking for, write 1 in the 29 place. Now, the value of 29, which is 512, is subtracted from 625. 625 - 512 = 113.
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, 113. So, the next largest power of 2 is 26, which is 64. Now, we have to write 1 in the 26 place. And then subtract 64 from 113. 113 - 64 = 49.
Step 4 - Repeat the process: Continue identifying the largest powers of 2 that fit into the remainder until you reach 0. 25 = 32, 49 - 32 = 17. 24 = 16, 17 - 16 = 1. 20 = 1, 1 - 1 = 0.
Step 5 - Identify the unused place values: In step 2 through step 4, we wrote 1s in the 29, 26, 25, 24, and 20 places. Now, we can just write 0s in the remaining places, which are 28, 27, 23, 22, and 21. Now, by substituting the values, we get: 0 in the 28 place 0 in the 27 place 1 in the 26 place 1 in the 25 place 1 in the 24 place 0 in the 23 place 0 in the 22 place 0 in the 21 place 1 in the 20 place
Step 6 - Write the values in reverse order: We now write the numbers upside down to represent 625 in binary. Therefore, 1001110001 is 625 in binary.
Grouping Method: In this method, we divide the number 625 by 2. Let us see the step-by-step conversion.
Step 1 - Divide the given number 625 by 2. 625 / 2 = 312. Here, 312 is the quotient and 1 is the remainder.
Step 2 - Divide the previous quotient (312) by 2. 312 / 2 = 156. Here, the quotient is 156 and the remainder is 0.
Step 3 - Repeat the previous step. 156 / 2 = 78. Now, the quotient is 78, and 0 is the remainder.
Step 4 - Repeat the previous step. 78 / 2 = 39. Here, the quotient is 39 and the remainder is 0.
Step 5 - Repeat the previous step. 39 / 2 = 19. Here, the quotient is 19 and the remainder is 1.
Step 6 - Repeat the previous step. 19 / 2 = 9. Here, the quotient is 9 and the remainder is 1.
Step 7 - Repeat the previous step. 9 / 2 = 4. Here, the quotient is 4 and the remainder is 1.
Step 8 - Repeat the previous step. 4 / 2 = 2. Here, the quotient is 2 and the remainder is 0.
Step 9 - Repeat the previous step. 2 / 2 = 1. Here, the quotient is 1 and the remainder is 0.
Step 10 - Repeat the previous step. 1 / 2 = 0. Here, the remainder is 1. And we stop the division here because the quotient is 0.
Step 11 - Write down the remainders from bottom to top. Therefore, 625 (decimal) = 1001110001 (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 625. Since the answer is 29, write 1 next to this power of 2. Subtract the value (512) from 625. So, 625 - 512 = 113. Find the largest power of 2 less than or equal to 113. The answer is 26. So, write 1 next to this power. Continue this process until you reach a remainder of 0. Final conversion will be 1001110001.
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, 625 is divided by 2 to get 312 as the quotient and 1 as the remainder. Now, 312 is divided by 2. Here, we will get 156 as the quotient and 0 as the remainder. Continue dividing the subsequent quotients by 2 until the quotient becomes 0. Now, we write the remainders upside down to get the binary equivalent of 625, 1001110001.
This rule also involves breaking of the number into powers of 2. Identify the powers of 2 and write it down in decreasing order i.e., 29, 28, 27, 26, 25, 24, 23, 22, 21, and 20. Find the largest power that fits into 625. 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 625, we use 0s for 28, 27, 23, 22, and 21 and 1s for 29, 26, 25, 24, and 20.
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 625.
Memorize to speed up conversions: We can memorize the binary forms for numbers through practice.
Recognize the patterns: There is a peculiar pattern when converting numbers from decimal to binary.
Even and odd rule: Whenever a number is even, its binary form will end in 0. For example, 4 is even and its binary form is 100. Here, the binary of 4 ends in 0. If the number is odd, then its binary equivalent will end in 1. For example, the binary of 5 (an odd number) is 101. As you can see, the last digit here is 1.
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 on a table will help us remember the conversions.
Here, let us take a look at some of the most commonly made mistakes while converting numbers to binary.
Convert 625 from decimal to binary using the place value method.
1001110001
29 is the largest power of 2, which is less than or equal to 625.
So place 1 next to 29.
Subtracting 512 from 625, we get 113.
The next largest power would be 26.
Place another 1 next to 26.
Continue this process until the remainder is 0.
By using this method, we can find the binary form of 625.
Convert 625 from decimal to binary using the division by 2 method.
1001110001
Divide 625 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 625 to binary using the representation method.
1001110001
Break the number 625 into powers of 2 and find the largest powers of 2.
We get 29. So 1 is placed next to 29.
Next, 625 - 512 = 113.
Now, the largest power of 2 is 26.
Once again, 1 is placed next to 26.
Continue the process until the remainder is 0.
Fill in with zeros for unused powers of 2.
By following this method, we get the binary value of 625 as 1001110001.
How is 625 written in decimal, octal, and binary form?
Decimal form - 625 Octal - 1161 Binary - 1001110001
The decimal system is also called the base 10 system. In this system, 625 is written as 625 only.
We have already seen how 625 is written as 1001110001 in binary.
So, let us focus on the octal system, which is base 8.
To convert 625 to octal, divide 625 by 8.
So 625 / 8 = 78 with 1 as the remainder.
In the next step, divide the quotient from the previous step (78) by 8. So 78 / 8 = 9 with 6 as the remainder.
Finally, 9 / 8 = 1 with 1 as the remainder. 1 / 8 = 0 with 1 as the remainder.
The division process stops here because the quotient is now 0.
Write the remainders in reverse order.
So, 1161 is the octal equivalent of 625.
Express 625 - 20 in binary.
1001101001
625 - 20 = 605 So, we need to write 605 in binary.
Start by dividing 605 by 2.
We get 302 as the quotient and 1 as the remainder.
Next, divide 302 by 2.
Now we get 151 as the quotient and 0 as the remainder.
Divide 151 by 2 to get 75 as the quotient and 1 as the remainder.
Continue dividing the quotients by 2 and noting the remainders until the quotient becomes 0.
Now write the remainders from bottom to top to get 1001101001 (binary of 605).
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.