SDCL § 47-1A-824: Quorum and voting.

Unless the articles of incorporation or bylaws require a greater number or unless otherwise specifically provided in this chapter, a quorum of a board of directors consists of:

(1) A majority of the fixed number of directors if the corporation has a fixed board size; or

(2) A majority of the number of directors prescribed, or if no number is prescribed the number in office immediately before the meeting begins, if the corporation has a variable-range size board.

The articles of incorporation or bylaws may authorize a quorum of a board of directors to consist of no fewer than one-third of the fixed or prescribed number of directors determined under this section. If a quorum is present when a vote is taken, the affirmative vote of a majority of directors present is the act of the board of directors unless the articles of incorporation or bylaws require the vote of a greater number of directors.