How many pictures on 4GB memory card in 16 mega pixel digital camera?

It depends on the format that pictures are being saved and the quality in which you're saving them.
  • If you're using uncompressed RAW (24 bits per pixel) format, then it's about ~70.
  • If you're using a kind of compressed format then it depends on the format and the quality. For JPEG, at 100% quality (loss-less compression) it's about ~710.