In the big battle called Titanomachia, no number is mentioned.
Zeus defeated the titans becuase Kronos ate all of his siblings.
...Powerful.
Because Prometheus helped the Zeus and his siblings defeat the other Titans.
In Greek mythology, Zeus was helped by his siblings, Poseidon, Hades, Hestia, Demeter, and Hera, to defeat their father Cronus and the Titans.
The consequences of the rebellion against Zeus by the Titans in Greek mythology were their defeat and imprisonment in Tartarus, a deep abyss in the underworld. Zeus and the Olympian gods emerged victorious and established their rule over the cosmos, with Zeus becoming the supreme ruler of the gods.
Two Titans sided with Zeus; Themis and Prometheus.
Zeus's mother saved him and hid him. Kronos had swallowed all the children. Zeus tricked his father into swallowing a boulder, then sliced him to shreds and threw him into Tartarus.
Gaea, mother of the titans, told Zeus how to overthrow the titans. She was appalled about how badly the titans were ruling the Earth.
Prometheus and Epimetheus were Titans that Zeus did not banish to Tartarus.
The titans were mostly imprisoned and Zeus became king of the gods
Hades or in Roman terms, Pluto
Zeus was helped by one Titan, Prometheus. Also by three Giants the ''Hecatonchires'' (monsters with one houndred hands) and the satyr Pan.