Because the mortgage takes a long time. The loan supply time is as long as several decades, so it is defined as the longest loan, which is represented by the number 9.

Major commercial banks have certain differences in the term of mortgage loans. In general, the longest loan period is 30 years. Some banks have other requirements, for example, the Agricultural Bank of China stipulates that the loan period and the borrower's age should not exceed 65. The Bank of China stipulates that foreign exchange loans cannot exceed eight years at the longest.