Knowing the Greek alphabet can help you gain a better understanding of Greek classics, as well as provide knowledge and reference in science and math where it requires you to know the Greek alphabet.  =  Required fields are marked *. What ACT target score should you be aiming for? The Classical alphabet had 24 letters, 7 of which were vowels, and consisted of capital letters, ideal for monuments and inscriptions. The Greek alphabet was developed about 1000 BCE, based on the Phoenician's North Semitic Alphabet. ,