70 Weeks Part 4

The emphasis in that quote of the verses is... do you see three breakdowns? Seventy weeks is broken down as seven weeks, sixty-two weeks and one week. Three parts. And we asked the question last time, "Why Three Parts?". Why seven, sixty-two and one? Particularly, why not sixty-nine and one? Seven plus sixty-two is sixty-nine. If it's going to be seven weeks and sixty-two weeks until Messiah the Prince, you could have said it easier by saying, "It's going to be sixty-nine weeks until Messiah the Prince, right?".
Why did God say it that way?