0o542

0o542 is a numeric literal that uses the octal (base-8) system, denoting a number with the digits 5, 4, and 2 in base 8. The prefix 0o is used in several programming languages to indicate octal literals, most notably Python.

In decimal form, 0o542 equals 354. This is calculated as 5 × 8^2 + 4 × 8 + 2 = 320 + 32 + 2 = 354. In Python, for example, the expression 0o542 evaluates to the integer 354, and int('542', 8) also yields 354. Before Python 3, octal literals were written with a leading 0 (such as 0542), but Python 3 introduced the 0o prefix to avoid confusion with decimal numbers.

Octal notation is structured so that each digit represents three binary bits, since 8 is 2^3. The digits 5, 4, and 2 correspond to the binary groups 101, 100, and 010, which together form the binary representation 101100010, equal to the decimal value 354. This relationship between octal digits and binary is a common feature of base-8 notation and can be useful when dealing with low-level data or bitwise operations.

Beyond programming, octal literals sometimes appear in discussions of Unix file permissions and other contexts where octal notation is convenient for representing bit fields. However, 0o542 itself is primarily encountered as a representation in code rather than as a standalone concept outside computing.