Your answer, "Zero", is not correct.
The correct answer to
How many sons did Michal have?
is
Five
as shown by
2 Samuel 21:8
which is
- KJV
- But the king took the two sons of Rizpah the daughter of Aiah, whom she bare unto Saul, Armoni and Mephibosheth; and the five sons of Michal the daughter of Saul, whom she brought up for Adriel the son of Barzillai the Meholathite:
- NIV
- But the king took Armoni and Mephibosheth, the two sons of Aiah's daughter Rizpah, whom she had borne to Saul, together with the five sons of Saul's daughter Merab, {Two Hebrew manuscripts, some Septuagint manuscripts and Syriac (see also 1 Samuel 18:19); most Hebrew and Septuagint manuscripts Michal} whom she had borne to Adriel son of Barzillai the Meholathite.