Here's Camping's calculation paragraphs from his "Another Infallible Proof":
Because of the importance and wonder of this proof we will take time to develop it. First we must learn that we can develop with perfect precision the number of days from one date to another. To obtain the precise number of days from a moment in one year to the same moment in any other year we must realize that astronomers have long ago discovered that there are 365.2422 days in a complete year. That is why in our modern calendar there are 365 days in each of three consecutive years. However, every fourth year has 366 days. This is done by adding an extra day in February of that year. Thus the average year for the four years becomes 365.25 days. But .25 is greater than .2422, so every 128 years a day is dropped from the calendar to maintain accuracy.Camping has made a mistake. The number of days from April 1, 33, to April 1, 2011, is actually 722,451 days (not 722,449.07). What about his proof? His proof is based on an assumption that April 1, 33, to April 1, 2011, are exactly 1978 years apart, and that a year is 365.2422 days.
Thus all we have to do is multiply the number of years separating two events by the number 365.2422 to know the exact number of days between them. So from April 1, 33 A.D. to April 1, 2011 there are exactly 2011 – 33 = 1,978 years, each having 365.2422 days. This equals 722,449.07 days. From April 1, 2011 to May 21, 2011 inclusively (including the first day and the last day) are 51 days. Adding these 51 days to the number 722,449.07 gives us exactly 722,500.07 days, from April 1, 33 A.D. to May 21, 2011 inclusively. This number is enormously significant. Presently we will see why this is so.
Camping's calculation allegedly provides the number of days as 722,449.07, although more precisely the number is 722,449.072. But there's a serious problem with the calculation. The number of days between April 1, 33, and April 1, 2011, is not a fractional number of days. It's an exact integer number of days. That's because the sun rises exactly once each day.
If you're not convinced, try a simple example: April 1, 2010, to April 1, 2011. Using Camping's method, that's one year, and consequently it is 365.2422 days. But, in fact, you can go get a calendar and count and verify that, in fact, it is exactly 365 days.
Also, keep in mind that the 365 number is based on counting only one of the two end days. This is the normal way of counting days. For example, we say that April 2 is one day from April 1. That's because we count only the last day (April 2) and not the first day (April 1). So, it is a little strange when Camping asks his readers to count 51 days based on counting both the first day and the last days ("From April 1, 2011 to May 21, 2011 inclusively (including the first day and the last day) are 51 days.")
Using this method means counting from April 1, 2010, to April 1, 2011, to be 366 days. Moreover, as we noted before, if one counts both the first and last days, the number of days from April 1, 33, to May 21, 2011, is actually 722,502 days.
It is also strange to see how some of his other calculations work:
Interestingly this same message of salvation or judgment being the result of the Gospel is hidden in the total number of years the Gospel was to be sent by the churches into the world. We have learned that the church age began immediately after Christ demonstrated how He suffered and died to make payment for sin. That was in the year 33 A.D. We learned that the church age officially began on Pentecost, May 22, 33 A.D. It continued exactly 1,955 full years until May 21, 1988 when the church age came to an end.A few points. 1) Why are days counted with the first and last day both counted, whereas years are counted normally? Those familiar with Camping's work should recognize this kind of arbitrary hermeneutic - a hermeneutic of convenience, if you will.
2) 1955 "full years" according to his 365.2422 number would be 714,048.501 days.
2) But the actual number of days from May 22, 33 A.D. to May 21, 1988 is exactly 714,051 days (including the end date) - which is indeed 1955 full years (including the end date).
Why April 1? According to Camping, April 1, 33 A.D. is when Christ was hanging on the cross, reminding people of the sacrifice he had already made before the foundation of the world.
However, April 1, 33 A.D. was a Wednesday, as you can see in the calculation results already discussed and as you can calculate for yourself (just enter month "4", day "1", and year "0033".
Incidentally, some programs may tell you that April 1, 33, was a Friday (input "4", "1" and "0033" here, for example), but if you look more closely, you will see that these are programs that are using a Gregorian calendar (back before the Gregorian calendar was even invented).
Incidentally, I suspect that this two days (of the week) difference is connected with the two-day error in Camping's calculations, but I am not sure.