Final answer:
There are 27 amendments to the U.S. Constitution, with the 27th and last amendment being added in 1992.
Step-by-step explanation:
The Constitution of the United States has been amended 27 times, with the first ten amendments known as the Bill of Rights. The process of amending the Constitution requires a proposal by a two-thirds vote in Congress or by two-thirds of state legislatures, and ratification by three-quarters of the state legislatures. The most recent, or last amendment added to the Constitution, was the 27th Amendment, which was ratified in 1992. These amendments have been added over the course of two centuries to address various issues and adapt the Constitution to the changing needs of the nation.