Total volume = Edge³. Additional water = Final volume − Initial volume.

• Total capacity = 18 × 18 × 18 = 5832 cm³
• Initial water = \(\frac{1}{9}\) × 5832 = 648 cm³
• If final = 5832 cm³ (full), additional = 5832 − 648 = 5184 cm³ = 5 l 184 ml
• Stored answer = 2 l 673 ml — verify question text for correct second fraction.

Final Answer: See key-conflict note — verify question text.