Albert Barnes Commentary Job 36:1

"Elihu also proceeded, and said," — Job 36:1 (ASV)

Elihu also proceeded - Hebrew added - ויסף vayâsaph. Vulgate “addens;” Septuagint, Ηροσθεὶς Eerostheis - “adding, or proceeding.” The Hebrew commentators remark that this word is used because this speech is “added” to the number that it might be supposed he would give. There had been “three” series of speeches, by Job and his friends, and in each one of them Job had spoken three times. Each one of the three friends had also spoken three times, except Zophar, who failed to reply when it came to his turn. Elihu had also now given three speeches, and here he would naturally have closed, but it is remarked that he “added” this to the usual number.