The number (123456)8 is equivalent to

Step 1 — Convert octal to binary: write each octal digit as 3 bits.

• 1 → 001, 2 → 010, 3 → 011, 4 → 100, 5 → 101, 6 → 110

Concatenate: 001010011100101110

Step 2 — Convert to hexadecimal: pad the binary on the left to make 4‑bit groups and convert each group.

• Pad left with two zeros: 00001010011100101110

• Groups: 0000 1010 0111 0010 1110 → hex digits 0 A 7 2 E → drop leading 0 → A72E

Step 3 — Convert to base 4: group the original binary into 2‑bit pairs (no left padding needed here).

• 2‑bit groups: 00 10 10 01 11 00 10 11 10 → digits 0 2 2 1 3 0 2 3 2

• Drop leading 0 → 22130232

Answer: the octal number 123456 (base 8) equals (A72E)16 and (22130232)4.