Here are some specific verses. Thanks!
Ezekiel prophesied a number of years in captivity:
“…As for you [Ezekiel], lie down…for the number of days…three hundred and ninety days (for Israel’s sin)…When you have completed these…I have assigned it to you for forty days (for Judah’s sin)…a day for each year.”—Ezekiel 4:4-6
That's 430 years (biblical years of 360 days each). 70 years of captivity were served in Babylon, leaving 360 years.
Modern atheists noted this... surely the final Jewish diaspora into modern times lasted more than 360 years since the end of the Babylonian captivity! Surely the Bible was wrong:
606 BCE …Judah/Israel taken captive to Babylon
536 BCE …Cyrus allows return to Israel
...360 years later is pre-Roman times in Israel!
Some readers, noticed, however, that Leviticus 26:14-46 says Israel will pay seven times over for disobedience: "…If also after these things you do not obey Me, then I will punish you seven times more for your sins."
They multiplied 7 times 360 360-day years from the Cyrus decree and in the Gentile calendar this comes out to: Whoa! May 14, 1948 CE! God left it as written to demonstrate it wasn't a self-fulfilled prophecy, and for skeptics to draw it out!
OK, so the punishment originally was to be 430 years starting in 606BCE. Instead, it should be multiplied by 7, so it should be 430x7=2910 years starting in 606BCE. Your calculation multiplied the *remaining* punishment after that 70 years and not the *total* punishment. Also, it says 7 times *more*, so this should be added *after* that 70 years, and depending on interpretation, after the original 430 years.
As an example, suppose someone is sentenced to 10 years, serves 3 and then their sentence is extended by 7 times more than their original punishment. How long would they spend in prison? At the least, the sentence would be 70 years in addition to the 3 and, more reasonably, to 70 years in addition to the original 10.
What about coincidence?
There are numerous Bible prophecies, these are the sole passages on the God-commanded length of the lengthy diaspora. The coincidence would be millions-to-one. There are similar precise number prophecies relating to other aspects, if you're interested. The date for Christ's crucifixion appears in the Septuagint, which scholars know dates to at least two-and-a-half centuries before Christ.
What about completely massaging the numbers until they come out to a previously established conclusion?