Possible Clues:

• 9, for 729
• One-third power
• Bruce too confused by this mathematical term
• Three, to 27
• One is one's own man, no longer leading Englishmen behind block
• Relationship of two to eight, for example
• Two for eight, perhaps -- it's a factor
• 4 of 64 or 5 of 125, for example
• The 'x' in x³
• Two of eight, perhaps, heading for unrest in October after revolution