Complex sentence: By 1901, there were an estimated 3,771 Jews in Ireland, over half of them (2,200) residing in Dublin; and by 1904, the total Jewish population had reached an estimated 4,800.
Split into simpler sentences: By 1901, there were an estimated 3,771 Jews in Ireland, over half of them (2,200) residing in Dublin. By 1904, the total Jewish population had reached an estimated 4,800.