Legal analysis: how many contracts need to be signed to buy a house, and the number is different according to the different ways of sharing money. Five mortgage loans, one for the customer, one for the company, one for the real estate bureau, one for the bank and one for the deed tax. The full payment and installment payment shall be made in quadruplicate, one for the customer's own use, one for the company's filing, one for the real estate bureau's filing and one for the deed tax payment.

Legal basis: Article 469 of the Civil Code of People's Republic of China (PRC). The parties may conclude a contract in writing, orally or in other forms. Written form refers to contracts, letters, telegrams, telexes, faxes and other forms that can tangibly express the contents contained. A data message that can tangibly express its content through electronic data interchange, e-mail, etc. , and can be retrieved at any time, are considered in writing.