At the end I mentioned another simple misconception from scripture and mentioned that there are others, but I did not elaborate. The thing is, as we move into real examples they get more complex and difficult to analyze. Whenever I am teaching physics there invariable comes the moment when a student actually gets curious and starts asking questions, not because they want to know what will be on the test, but they genuinely want to know how things work. When that happens we have to move into real world examples, and that is when things get complex because all the simplifications and assumptions we made previously now are invalid. Now there is friction. Strings, springs and pulleys have mass. Density is not uniform, gravity is not constant, and we suddenly start talking about things like the Lagrangian, probabilities and distributions.
On that note, this example is a little more complex but still on the simple side.
One criticism of the Book of Mormon is that it gets certain dates wrong. It is very clear that there were 600 years between when Lehi left Jerusalem (during the first year of king Zedekiah) and the birth of Christ. This accounting was not approximate but exact. But as critics of the Book of Mormon like to point out Zedekiah became king in 597 BC and Christ was born in 4 BC (±1), which comes to 593±1 years, not 600.
But here's the thing, calenders are funny things. Not all calenders have 365 days per year. The Jewish lunar calender has 354±1 days per year. And the Mayan calender (the Mayans, and their neighbors, are the closest culturally to the people of the Book of Mormon that we know of, if not the actual people of the Book of Mormon), has 360 days per year. So if we take 600 years according to the Mayan calender we get:
360*600 = 216000 daysWhich translates to:
216000/365 = 591.8 solar yearsStill not an exact match with 593±1 years but it does line up a lot better. If we use the Jewish calender it comes to 581.9 solar years. But as I pointed out calenders are funny things and how calenders are kept is particular to each culture and people. The problems only arise when we assume that everyone uses a solar calender. We just have to keep in mind that a year may not be year depending on which calender you use.
As an interesting side note, the mesoamerican long count calender is very interesting. The first day on the long count calender is denoted as 0.0.0.0.0. Mayans use a base 20 counting system. So after 20 days (0.0.0.0.19) it rolls over to the next digit (0.0.0.1.0). The second digit is funny since it only goes up to 18. So 0.0.1.0.0 follows 0.0.0.18.19. That means that 0.0.1.0.0 = 360 days, hence the 360 days per year according to the Mayans. So as we go to higher dates, 0.1.0.0.0 = 7,200 days and 184.108.40.206.0 = 144,000 days.
Each of these digits has a name in Mayan. As explained on Wikipedia,
"The Maya name for a day was k'in. Twenty of these k'ins are known as a winal or uinal. Eighteen winals make one tun. Twenty tuns are known as a k'atun. Twenty k'atuns make a b'ak'tun."So if we wanted to express something like "it's been 420 years since such and such happened", for some strange reason, we would say "it's been one b'ak'tun and one k'atun since such and such happened". Or put another way, 220.127.116.11.0 = 400 Mayan years + 0.1.0.0.0 = 20 Mayan years -> 18.104.22.168.0 = 420 Mayan years. But I should point out that these are Mayan years so according to our calender it has only been 414 solar years.
So when Moroni said that "more than four hundred and twenty years have passed away" what he most likely said was "it's been more than one b'ak'tun and one k'atun". Which could mean that it has been exactly one b'ak'tun one k'atun (22.214.171.124.0) or it could mean that it was anywhere between one b'ak'tun one k'atun (126.96.36.199.0) and one b'ak'tun two k'atun (188.8.131.52.0) depending on how exact Moroni was being. So it could range from 420 Mayan years to 439 Mayan years, which would translate to between 414 and 433 solar years. So even though the Church has tried to be helpful by including the years on the bottoms of the pages in the Book of Mormon, they may be off by several years depending, because we unconsciously assumed that the Nephites used a solar year for their calender.