At least percent of the states have to ratify an amendment for it to become official.

At least 75 percent of the states have to ratify an amendment for it to become official.

Explanation:

After the official proposal, a constitutional amendment has to be ratified by the legislatures of, or by conventions within, at least three quarters of the states, as stated by the Article Five of the Constitution of the United States.

An amendment can be adopted and sent to the states for ratification in two ways: by decision of two-thirds of both houses of the Congress or by means of a National Convention convened to amend the Constitution at the request of at least two-thirds of the states.

To become part of the Constitution, an amendment must be ratified by at least three fourths of all states (currently 38 states) in one of two ways (the method is determined by Congress): either by voting in the state legislatures or by voting on specially conventions in each state.