HONG KONG — Maybe it was just a coincidence, but when the Shanghai Stock Exchange fell 64.89 points on Monday — uncannily echoing the date of the Tiananmen Square crackdown on pro-democracy students on June 4, 1989, exactly 23 years earlier — the Chinese blogosphere went into a tizzy.

“I want to thank all the stock traders!” wrote one microblogger.

“Maybe God does exist?” wrote another.

Whatever the reason, the strange trick that the stock market played on the Chinese Communist Party sent the country’s censors scrambling as well, prompting them to undertake unusually strenuous efforts to block references to the tragedy, which Chinese leaders have tried desperately to erase from their country’s consciousness.

In a nation where numerology is taken very seriously, the censors quickly began blocking searches for “stock market,” “Shanghai stock,” “Shanghai stock market,” “index” and related terms. They also deleted large numbers of microblog postings about the numerical surprise.