Reply To: Classics and Beyond Bo – Cups, Captivity, and Calculations:

The tribe of Ephraim miscalculated 400 years from bris ben habsorim but it really was 430, thirty years before their promised redemption, where the 400 years was from the birth of Yitzchak. This caused them to get killed. The Targun Yonason in the beginning of Parashas Beshalach explains that Hashem took the Jews in a round about away in order they should not see the 200,000 dead corpses that Yesezkel Hanavi saw being ressurected in the atzamas yeveshos prophesy.