.
 = 8.96 (approximately).
Therefore, the number under the question should be close to 8.96 from the lower side.
Inspired by this observation, I write  720 = 8*9*10,  using factors that are close to 8.96.
From this decomposition, it is clear that the answer is 8.
 = 8.96 (approximately).
Therefore, the number under the question should be close to 8.96 from the lower side.
Inspired by this observation, I write  720 = 8*9*10,  using factors that are close to 8.96.
From this decomposition, it is clear that the answer is 8.
Solved.