I see it as this:
250 Million OW (250 Total) (Crosses Transformers Domestic Box office)
180 Million Monday-Thursday (Christmas week) (450) (Crosses Avengers Ultron Box office)
180 Million 2nd weekend (Christmas weekend) (610)
130 Million Monday-Thursday (new Years week) (740) (Crosses Titanic Box office)
110 Million 3rd weekend (New years weekend) (850) (Crosses Avatar Box Office)
$850 million by the end of the third weekend. Am I reading this correctly?