Original: Eusebius of Caesarea counted 250, Athanasius of Alexandria counted 318,Ad Afros Epistola Synodica 2 and Eustathius of Antioch counted 270Theodoret H.E. 1.7 (all three were present at the council).
Simplified: Eusebius_of_Caesarea counted 250, Athanasius_of_Alexandria counted 318,Ad Afros Epistola Synodica 2 and Eustathius_of_Antioch counted 270Theodoret H.E. 1.7 (all three were present at the council).