Historical allusions use 7
The Seven Heroes in the Warring States Period, the Rebellion of the Seven Kings in the Western Han Dynasty, Zhuge Liang's capture of Meng Huo in the Three Kingdoms Period, Cao Zhi's Seven-step Poems, Elvis Presley in the Northern Song Dynasty, Yu Qi Uprising in Shandong in the Early Qing Dynasty, Seven Gentlemen in the South of the Yangtze River, the July 7th Incident (Lugouqiao Incident) in the Republic of China, and the Seven Gentlemen Incident concocted by the Kuomintang, etc.