I seen a lot of narrations that have different answers to this question and a few are like he had 99, 100, 700 or even 1000 wives. Is this an Allah knows Best question or something that actually has a valid answer?
It is not known.
There is an incident mentioned in hadith where Solomon عليه السلام swears that he would sleep with his women and each would give birth to a child who would fight in the cause of Allah. The transmitters of the hadith differed in the number of women that they were sixty (Bukhari 7469), seventy (Bukhari 3424), ninety (Bukhari 6639), ninety-nine (Bukhari 2819) , or a hundred (Bukhari 5242).
This can be explained as follows: They were actually ninety-nine women; sixty were his wives and the rest were concubines. The variants exist because of rounding the numbers to make it even; and because of combining the different categories of women or omitting one category:
Some of the narrators have only mentioned the number of wives and omitted the concubines (these are those which record 60 or 70) while others have combined the two types (those which record 90, 99 or 100)
Some of the narrators have rounded the numbers up, they have rounded up the actual number of wives from 60 to 70, while others have rounded up the total number of women from 99 to 100, while some have rounded it down to 90.
Further, this hadith does NOT imply the total or maximum number of his wives. Rather it is possible that he only made this oath about a small subset of his women. And it also is possible that he later married more women.
Some of the scholars have recorded that he had 1000 women consisting of 300 wives and 700 concubines. This report is not authentically attributed to the Prophet ﷺ and is probably narrated from the Bani Israel (a similar report is recorded in their scripture 1 Kings 11:3), so it may or may not be correct.
Reference: Fath al-Bari