How many known children did king Solomon have?

15 sons and 1 daughter

Amnon,Daniel,Absalom,Adonijah,Shephatiah and the sixth, Ithream. These six were born to David in Hebron.These were the children born to him in Jerusalem:Shammua, Shobab, Nathan and Solomon. These four were by Bathsheba daughter of Ammiel.There were also Ibhar, Elishua, Eliphelet,Nogah, Nepheg,Japhia,Elishama, Eliada and Eliphelet-nine in all.All these were the sons of David, besides his sons by his concubines. And Tamar was their sister.