In Daniel 9:24-26, the angel Gabriel describes the end of days to Daniel:
Seventy weeks are determined upon thy people and upon thy holy city, to finish the transgression, and to make an end of sins, and to make reconciliation for iniquity, and to bring in everlasting righteousness, and to seal up the vision and prophecy, and to anoint the most Holy.
Know therefore and understand, that from the going forth of the commandment to restore and to build Jerusalem unto the Messiah the Prince shall be seven weeks, and threescore and two weeks: the street shall be built again, and the wall, even in troublous times.
And after threescore and two weeks shall Messiah be cut off, but not for himself: and the people of the prince that shall come shall destroy the city and the sanctuary; and the end thereof shall be with a flood, and unto the end of the war desolations are determined.
Babylon destroyed Jerusalem in 586 BC, and Daniel was one of the youths that were taken captive back to Babylon; the Jewish people were held captive for 70 years in Babylon, so the visit by the angel Gabriel occurred sometime near the end of this 70-year period, probably around 520 BC. Soon, Babylon was overcome by the Medeo-Persian empire, and Artaxerxes ascended the throne in 465 BC.
The prophecy states “From the going forth of the commandment to restore and rebuild Jerusalem” which occurred on March 4, 444 BC*, when Artaxerxes issues the decree to rebuild Jerusalem.
So let us add the weeks – threescore and two is 62 weeks, plus seven weeks leads us to 69 weeks. Weeks refers to weeks of years, so we can multiply 69 x 7 and arrive at 483 biblical years (biblical years are years with 360 days**). Multiply 483 x 360 to arrive at 173,880 days. Now divide by 365.25 and we end up with 476 years.
Now add 476 years to 444 BC, and you get to the spring of 33 AD (remember there is no year “0”, so we go directly from 1BC to 1AD). Which is when many scholars say that Yeshua (Jesus) was crucified or “cut off“. Note that in verse 9:26 the threescore and two weeks are preceded by the seven weeks. The Messiah was “cut off” not for himself, but for all of us who believe on Him for our salvation, as the sacrificial lamb of God.
Now there is a final week, spoken of by the angel Gabriel, in Daniel 9:27. This final week is the week which is yet to be fulfilled, which spans the seven years of the tribulation.
* Sir Robert Anderson proposes this date to be March 14, 445 BC. Either way, since we do not know the exact year that Yeshua was crucified, the prophecy is as close as one could hope for.
** 360-day years may sound contrived, but there is biblical evidence for such a number. In Genesis 7 and 8 we read about a 150-day flood that consisted of 5 months of 30 days each. And in Revelation 11:2-3, 12:6, and 13:5-7, we read about a three-and-a-half year period that consists of 1260 days (360 x 3.5).
Other opinions: http://www.promiseofhiscoming.com/ts_360_day_prophetic_year.htm