How many Supreme Court justices are usually needed to decide a case?

Why this is the answer

Five justices are usually needed to decide a case. A Supreme Court decision takes a majority, which means more than half of the justices voting the same way, and when all nine hear a case, the smallest possible majority is five. The word "usually" in the question is there for a reason. The study guide states the rule for the normal case, when nine justices hear a case: at least five must vote the same way. The official answer is five, and that is what the officer expects to hear. The process has a clear order. After the Court reviews a case, the justices meet, discuss it and vote. The Chief Justice serves as the Court's leader, yet each justice makes their own decision when voting. When a majority agrees, those justices write a decision explaining their reasons, and that becomes the ruling of the Court. Comparing majorities across the government helps, because the test asks about several of them. Congress also passes bills by simple majority: 218 votes in the House, where there are 435 voting members, and for most bills 51 votes in the 100-member Senate. Overriding a presidential veto is harder. Under Article I, Section 7, two-thirds of each chamber must vote to pass the bill again. The Supreme Court needs no supermajority of that kind; a bare majority is enough. Nine is wrong because it assumes every justice must agree. A unanimous decision is possible, but the rule does not require one. Six is two-thirds of nine, the kind of supermajority a veto override needs, and the Court has no such rule. Seven sounds plausible but has no basis. The arithmetic does the remembering for you. Half of nine is four and a half, so five is the first whole number past the halfway mark, and that is the majority.