How many seats are on the Supreme Court?

What does this answer mean?

There are nine seats on the Supreme Court: one Chief Justice and eight associate justices.

The Constitution doesn't set the number. Congress does, by law. The first Judiciary Act, in 1789, set it at six, and over the years the number has gone as low as five and as high as ten. The Judiciary Act of 1869 fixed it at nine, and it hasn't changed since.

Justices are nominated by the president and confirmed by the Senate. When a seat becomes empty because a justice retires or dies, the president nominates someone new. Since justices serve during good behavior, usually for life, a seat may stay with the same person for decades.

Six justices make a quorum, the minimum number needed to decide a case. With all nine taking part, five votes form a majority, which is the answer to another question on the test.

At the interview, say "nine."