One of the great numerical puzzles of the Torah is solved openly by Targum Pseudo-Jonathan on Exodus 12:40. The Hebrew says Israel lived in Mizraim for four hundred thirty years. But the genealogies do not add up to that number. Kehath, Levi's son, went down to Egypt, and his grandson Moses came back out. That is three generations, not the twelve or fifteen you would expect across four centuries.
The Targum resolves the tension with precision. The actual sojourn in Egypt was "thirty weeks of years" — thirty times seven — which is two hundred ten years. The full four hundred thirty years began earlier, from the hour the Lord spoke with Abraham on the fifteenth of Nisan, between the divided parts of the covenantal sacrifice (Genesis 15:17). The clock of exile started at the brit bein habetarim, the Covenant Between the Pieces, not at the descent to Egypt.
This reading preserves both the Torah's number and the genealogical arithmetic. Israel spent 210 years physically in Egypt. But the exile began the moment Abraham was told his descendants would be strangers in a land not their own. The rabbis saw this as a deep statement about how time is measured. God counts not from the arrival of the first slave but from the promise that once foretold him.
The Targum also notes that the Covenant Between the Pieces fell on the fifteenth of Nisan — the very date on which Israel would later leave Egypt. Abraham had stood with the torches moving between the animal halves on the same night that his descendants would later walk out under cover of the clouds of glory.
Takeaway: Israel was in Mizraim for 210 years. The exile itself lasted 430, dating from Abraham's vision. God had been counting for centuries before the bricks were even made.