а) 513:
$$513 = 8 \cdot 64 + 1 = 1001_8$$
б) 600:
$$600 = 8 \cdot 75 + 0$$
$$75 = 8 \cdot 9 + 3$$
$$9 = 8 \cdot 1 + 1$$
$$600 = 1130_8$$
в) 2020:
$$2020 = 8 \cdot 252 + 4$$
$$252 = 8 \cdot 31 + 4$$
$$31 = 8 \cdot 3 + 7$$
$$2020 = 3744_8$$
Ответ:
а) $$1001_8$$
б) $$1130_8$$
в) $$3744_8$$