[projektfu]

2/3 of states required to call a convention, 3/4 of the convention (which includes the states that show up, not just the callers) to amend the constitution.

Or 2/3 majority of both houses to propose and 3/4 of state legislatures to ratify amendments.

[Dalewyn]

It would appear I had remembered the wrong specific number, so thanks for that refresher!