Srimad Bhāgvat has 12 Skandhs, 325 adhyāys. Māhātmya from Padma Purana has 6 adhyāys and from Skandh Purana has 4 adhyāys. Thus Srimad Bhāgvat together with Māhātmya has 325+6+4= 335 adhyays. It originally had 18000 slokas but with passage of time some of them are lost. Unfortunatly, some Bhāgvat narrators (kathākārs) do not narrate the Māhātmya from Skandh Purana even though it contains some very important information such as explanation of four types of discourses named Nirguna, Sattvik, Rājas and Tamas. In my Bhāgvat discourses, the Māhātmya from Skandh Purana is always included.