Exhibit Numbers

Exhibit numbers are always in figures -- even at the beginning of a sentence. The word "exhibit" is capped in front of the number. The word "number" is abbreviated as "No."; the plural is "Nos."

...THE COURT: This will be Exhibit No. 4.
...MS. RAY: 4. Okay.

...We have marked this as Exhibit 9.

Happy punctuating!