Converting between Representations

With effort, you could directly translate between octal and hex notation. But it is much easier to use binary as an intermediate:

octal  →  binary  →  hexadecimal

You can convert a representation of a number in base B directly to a representation in base Y. But it is usually more convenient to use decimal or binary as an intermediate:

Base B  →  Decimal  →  Base Y

Base B  →  Binary   →  Base Y

Which intermediate to pick depends on the problem.