And they embittered their lives

"וַיְמָרְרוּ אֶת חַיֵּיהֶם" - and they embittered their lives... (Shemos 1:14)

Hashem told Avraham that his children would be in Egypt for 400 years, and yet they left after 210! 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:

ש"הקבה חשב את הקץ - Hashem reckoned the end. What is this talking about? Hashem hastened the גאולה and reckoned off קץ - 190 (from 400)- leaving us with 210!

The problem with the suggestion that the slavery was overly bad (if such a term can be used by slavery!) is that we don't see it anywhere - but the Vilna Gaon deals with this!

The notes on וַיְמָרְרוּ אֶת חַיֵּיהֶם are קדמא ואזלא, the numerical value of which is 190! They were embittered to a value of 190!

R’ Yosef Chaim Sonnenfeld points out that the גאולה from Egypt was only completed 7 days after it began, when the Red Sea when Paroh and his army were destroyed, so where is this reflected in events?

He answers that Isaac was only circumcised 7 days after his birth – so only then he became Jewish, and only 400 years from then were the Jews really free.