Convert numeric octal permission codes like 755 or 644 into readable rwx notation.
Each octal permission digit is the sum of read (4), write (2) and execute (1) for that class of user. Toggling the checkboxes for owner, group and others rebuilds each digit from the checked bits, producing both the 3-digit octal code and the equivalent symbolic string, plus a ready-to-run chmod command.
Octal digit from bits
digit = 4×read + 2×write + 1×execute
These are powers of two (2^2, 2^1, 2^0), so any combination of the three permissions maps to a unique digit from 0 to 7, exactly matching a 3-bit binary value.
755 (rwxr-xr-x) is common for executable scripts and directories: the owner gets full control while group and others can read and execute but not modify.
644 (rw-r--r--) is typical for regular files: the owner can read and write, while group and others can only read.