In the enslavement in Egypt, we are told how:
וַיְמָרְרוּ אֶת חַיֵּיהֶם” – and they embittered their lives… (Shemos 1:14)
Hashem told Avraham that his children would be enslaved in a land not their own for 400 years. Yet we find that they left after just 210 years of actual enslavement. Where are the missing 190 years?
There is an answer suggested that Egypt treated the Jews much worse than they should have, so as we say in ברוך המקום during Seder night:
ש”הקבה חשב את הקץ – Hashem reckoned the end. What “end” is this talking about? Hashem hastened the גאולה and reckoned off קץ - 190 (from 400)- leaving us with 210.
The Vilna Gaon points out how this is very subtly hinted to by the notes on וַיְמָרְרוּ אֶת חַיֵּיהֶם are קדמא ואזלא, which means “they got up and went”. Additionally, the numerical value of this is 190! They were over-embittered to a value of 190, so they got up an went!
R’ Yosef Chaim Sonnenfeld points out that the redemption from Egypt was only completed 7 days after it began, when the Red Sea parted and when Paroh and his army were destroyed, so where is this reflected in events?
He answers the 400 years were counted from Yitzchak’s birth. The extra week is found at his circumcision. Yitzchak was only circumcised 7 days after his birth – so only became Jewish then, and only 400 years from then were the Jews genuinely free.