Question

How many amendments are there?

Answer 1

There are 27 amendment to the U.S. Constitution.

Answer 2

There are twenty seven amendments (changes) to the US Constitution. One of them (the 21st) is simply the repeal of a different one (the 18th, prohibition).
Amendment I [Religion, Speech, Press, Assembly, Petition (1791)]
Amendment II [Right to Bear Arms (1791)]
Amendment III [Quartering of Troops (1791)]
Amendment IV [Search and Seizure (1791)]
Amendment V [Grand Jury, Double Jeopardy, Self-Incrimination, Due Process (1791)]
Amendment VI [Criminal Prosecutions - Jury Trial, Right to Confront and to Counsel (1791)]
Amendment VII [Common Law Suits - Jury Trial (1791)]
Amendment VIII [Excess Bail or Fines, Cruel and Unusual Punishment (1791)]
Amendment IX [Non-Enumerated Rights (1791)]
Amendment X [Rights Reserved to States (1791)]
Amendment XI [Suits Against a State (1795)]
Amendment XII [Election of President and Vice-President (1804)]
Amendment XIII [Abolition of Slavery (1865)]
Amendment XIV [Privileges and Immunities, Due Process, Equal Protection, Apportionment of Representatives, Civil War Disqualification and Debt (1868)]
Amendment XV [Rights Not to Be Denied on Account of Race (1870)]
Amendment XVI [Income Tax (1913)]
Amendment XVII [Election of Senators (1913)
Amendment XVIII [Prohibition (1919)]
Amendment XIX [Women's Right to Vote (1920)
Amendment XX [Presidential Term and Succession (1933)]
Amendment XXI [Repeal of Prohibition (1933)]
Amendment XXII [Two Term Limit on President (1951)]
Amendment XXIII [Presidential Vote in D.C. (1961)]
Amendment XXIV [Poll Tax (1964)]
Amendment XXV [Presidential Succession (1967)]
Amendment XXVI [Right to Vote at Age 18 (1971)]
Amendment XXVII [Compensation of Members of Congress (1992)]