You may need no supports or you may need more, only an engineer or
architect can say. I sized a steel beam replacement that allowerd the
removal of 3 supports, one every 8 feet. Go with less only if you take
exact spot measurements of floor to ceiling on every floor and monitor
it for a year or more and every year to see if settling occurs,
enginers-architects will over size you to not be liable. You might be
oversized but who knows.