How can anyone calculate 3 full days and 3 full nights from late Friday afternoon to the dark morning hours of Resurrection Sunday?

Answer 1

It's important to read the Biblical record carefully and not add our personal perceptions into the Text. The New Testament nowhere speaks of three "full" days.
In Jewish thought, any portion of a day constitutes a day. We do the same. When I say, "I spent the day shopping" it doesn't mean that I spent 24 hours shopping, but that I spent a portion of the day doing so.

If you count Friday afternoon, the entirety of Saturday, and the first few hours of Sunday ... that makes "three days."

Matthew 27:64; 1 Corinthians 15:4

Answer 2

You simply cannot. There are all sorts of convoluted calculations given by many to attempt to satisfy the only sign Christ gave for His Messiahship. But let's first make a correction to the common idea that the Scripture does not say 3 days AND 3 nights anywhere - see below:

Matthew 12:39-41New International Version (NIV)39 He answered, A wicked and adulterous generation asks for a sign! But none will be given it except the sign of the prophet Jonah.40 For as Jonah was three days and three nights in the belly of a huge fish, so the Son of Man will be three days and three nights in the heart of the earth.41 The men of Nineveh will stand up at the judgment with this generation and condemn it; for they repented at the preaching of Jonah, and now something greater than Jonah is here.

Jesus noted that there were 12 hours in a day and by default then 12 hours in the night since our days are 24 hours:

John 11:9New International Version (NIV)9 Jesus answered, Are there not twelve hours of daylight? Anyone who walks in the daytime will not stumble, for they see by this world's light.

So if we use the example given below, the absolute best one can calculate with partial days is: a few moments of Friday day; Friday night; all day Saturday and Saturday night; part of the early morning of Sunday - though Jesus was already arisen. This then is 3 days and only 2 nights. It doesn't fit the only sign Jesus gave mankind via the crowd present.

It is impossible to have a Friday crucifixion and a Sunday morning resurrection and satisfy the only sign Jesus gave of His Messiahship. But the next question is 'Did Jesus misspeak or lie?' Not at all.

If we realize the Jewish practices of the 7 Annual Holy Days which Jesus, born a Jew followed along with His Apostles, then we read in Scripture how He had His last meal on Passover evening or the first part of the Jewish day (our Tuesday evening) - counted from Genesis 1:5,8,13 and Leviticus 23L32 as sunset to sunset and not the Roman midnight to midnight - we see Him taken prisoner and tried, scourged and crucified on the daylight portion of Passover (Wednesday day). They requested His body before the 'high Sabbath' of the first Day of the Feast of Unleavened Bread beginning at sunset on the Roman Wednesday and Jewish Thursday). As many point to 31 AD as the year of this event, the Passover began Tuesday evening and Christ died at 3:00 PM Wednesday afternoon.

He was entombed just before sunset (Matthew 27:57-60) which would begin Wednesday evening - NIGHT 1. All night and day Thursday is Day 1; Night 2. The women bought spices for His body on the 'Preparation Day' or daylight portion of Friday Day 2 but could not break the coming weekly Sabbath rules of working so they waited (Mark 16:1; Luke 23:56). Friday Night 3; Saturday Day 3 just before sunset Saturday - total of 72 hours fulfilling the sign of Jonah. Then the women brought the spices in the early dark of the morning (Luke 24:1; John 20:1) but Jesus was already arisen (Matthew 28:1-6; Mark 16:2-6; Luke 24:2-3; and John 20:1). He arose on Saturday - He is Lord of the Sabbath (Matthew 12:8; Mark 2:28; and Luke 6:5).

Wednesday death and burial just before sunset to Saturday Resurrection just before sunset being seen by the women in the early morning dark hours of Sunday - the first day of the week.
Curiously, mainstream Christianity celebrate 'Pentecost' on a Sunday which is totally correct. But this date represents 50 days (meaning of date) after the Resurrection of Christ. If it were on Sunday, then 7 weeks or 49 days would be a Sunday and 1 more day would be Monday. This is not correct even for these worshippers. But if the Resurrection was on a Saturday as presented above, then 7 weeks or 49 days would be a Saturday and 1 more day would be Sunday, 17 Jun 31 AD, which is correct.