how many of the original thirteen states must ratify/approve the constitution for it to take effect?

Nine of the original thirteen states had to ratify the U.S. Constitution for it to be adopted. This requirement was set by Article VII of the Constitution, which called for ratification by just nine states, or a two-thirds majority, rather than unanimous approval. This threshold was met when New Hampshire became the ninth state to ratify on June 21, 1788, officially enacting the Constitution and ending government under the Articles of Confederation.