[Grammar] Missing verb in a relative clause

[khanhhung2512]

In this link U.S. GOVERNMENT > The Three Branches > Judicial Branch > How U.S. Courts Work I found the following sentence:
As in the federal court system, trials are presided over by a single judge (often sitting with a jury); entry-level appellate cases are heard by a three-judge panel; and in state supreme courts, cases are heard by all members of the court, which usually number seven or nine justices.
I'd like to ask whether the sentence above is grammatically correct, because I think the clause in bold misses a verb.
Thanks in advance.
PS: Please let me know if there are any mistakes in my post.

 

[SoothingDave]

"Number" is a verb here.

 

[Raymott]

In this link U.S. GOVERNMENT > The Three Branches > Judicial Branch > How U.S. Courts Work I found the following sentence:
As in the federal court system, trials are presided over by a single judge (often sitting with a jury); entry-level appellate cases are heard by a three-judge panel; and in state supreme courts, cases are heard by all members of the court, which usually number seven or nine justices.
I'd like to ask whether the sentence above is grammatically correct, because I think the clause in bold misses a verb.
Thanks in advance.
PS: Please let me know if there are any mistakes in my post.

The verb in that sentence is "number".

[h=3]num·ber/ˈnəmbər/
[/h]

Verb:	Amount to (a specified figure or quantity); comprise: "the demonstrators numbered more than 5,000".

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