Inside and outside, we have 57! But they are never all on at once.
Sitting/dining room: 2 ceiling fittings with 3 bulbs each in main part, one central fitting in dining part, one standard lamp, one wall lamp, one lamp that lights a slice of quartz from behind and a light in a glass fronted cupboard =11, but we usually have either the ceiling or the other lights on
Family room: 3 wall lights, one 3xbulb spotlight bar over the desk which is only on if someone's working there = 6
Kitchen/utility: 8x low voltage halogen spotlights, one fluorescent tube over the ironing board,one light in washing-machine area, 3 under-cupboard lights, 1 over-hob light, lights in oven, fridge & microwave =17
Cloakroom/hall/stairs: Total of 5 including one in understairs cupboard
Bedrooms: Central light & bedside light in each of 4 bedrooms, plus light over basin in one room = 9
Bathroom: Central light, light over basin, light in alcove containing wall cabinet = 3
Outside & loft: 2 in loft, 1 in garage, 2 in passage from back door to side gate, 1 by front door = 6
AS I say, they are never all on & they are nearly all low power bulbs, so we don't use that much electricity - in fact Southern Electric currently owe us rather a lot...