Decimal to Octal Converter

Convert decimal integers to octal with a step-by-step division-by-eight breakdown showing remainders and the final octal string.

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Also in Number Theory

Number Systems

Decimal to octal: convert base-10 numbers to base-8

The decimal to octal converter translates decimal (base-10) integers into their octal (base-8) equivalents. Enter a decimal number and see the octal result with a step-by-step division breakdown.

How the conversion works

Repeatedly divide the decimal number by 8 and record the remainder at each step. Read the remainders from bottom to top to form the octal result.

For example, decimal 100 divided by 8 gives quotient 12 remainder 4, then quotient 1 remainder 4, then quotient 0 remainder 1, producing octal 144.

Where octal is used

Octal notation is most commonly seen in Unix and Linux file permissions. The permission triplet for owner, group, and others is specified as a three-digit octal number, such as 755 for full owner access with read-execute for others.

Frequently asked questions

What digits appear in octal?

Only digits 0 through 7. Any digit 8 or 9 would be invalid in base 8.

Why is octal used for file permissions?

Each permission set (read, write, execute) maps to three bits, and three bits map perfectly to one octal digit, making octal a natural fit.

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