1) The Jewish calendar is lunar based and each month starts with a New Moon. (
Judaism 101)
2) A Synodic Month (New Moon to New Moon) is 29.530589 days. (
NASA)
Robert Anderson says on
page 55 of his book "The Coming Prince"...
"The
1st Nisan in the twentieth year of Artaxerxes (the edict to rebuild Jerusalem) was 14th March,
B. C. 445. The
10th Nisan in Passion Week (Christ's entry into Jerusalem) was 6th The Coming Prince text by Sir Robert Anderson 55 of 158 April,
A. D. 32."
And on
page 56 he says...
"69 weeks of prophetic years of 360 days (or 69 x 7 x 360)
173,880 days."
So he tries to prove that it is exactly 173,880 days from Nisan 1, 445 BC to Nisan 10, 32 AD.
But rather than just calculate the number of days between two dates on the Jewish Calendar,
he first tries to convert the Jewish dates into Gregorian dates, and then calculate the number of days between the two Gregorian dates.
But it is much easier to
calculate the number of days using the original Jewish dates, Nisan 1, 445 BC and Nisan 10, 32 AD.
Here is the simple Math...
Each Jewish month starts with a New Moon.
There are 29.530589 days in a Synodic Month (New Moon to New Moon).
So there are 5888
.1318 Synodic Months in 173,880 days (173,880 / 29.530589).
So there are 5888 Synodic Months plus
3 or 4 days (
.1318 * 29.530589) in 173,880 days.
That means...
If the starting date was on Nisan
1, the ending date had to be on Nisan
4 or 5 (Nisan 1 plus
3 or 4 days).
Not Nisan 10.
Robert Anderson was off by 5 or 6 days.
P.S.
Robert Anderson arbitrarily chose Nisan 1 as the starting date (the Bible states the month, but Robert Anderson chose the day). He could have just chosen Nisan 6 or 7 as the starting date, and then his calculation would have worked. I mean, if you are going to arbitrarily pick dates, you may as well pick one that works.