The number 40 appears in several biblical stories. Such as, 40 days and 40 nights of Noah's flood story, Jesus walked on the earth for 40 days, etc. I read on Wikipedia that 40 is use as an approximate number and not an exact number, something similar to "umpteen". However I wouldn't call Wikipedia an authoritative source (is SE better? :) ). My question is, what sources do we have to back up or disprove the use of the number 40 as a general number and not an exact number?
Forty is a round number designating a fulness of time according to Kittel:
On the linguistic problems of the stems τεσσαρ- and τεσσερ- → 127, 6 ff. Forty plays an important role in many civilized and uncivilized peoples as a number for specific periods of days and years, for numbers of men and things.1 It is gen. used as a round number. in Bab. kissatum can be added, “totality,” “fulness.” It is esp. important among the Mandaeans, the Arabs and other Islamic peoples, and African and Red Indian tribes. In Gk. it is found a. as a round no., for 40 yrs. as a long time, e.g., of a war (TDNT, Kittel)
I think the supporting evidence for this view would be the frequent use of the word forty, even when their does not seem any religious deep significance which may have corresponded to a literal measure. For example, in Acts 4:22 the age of a person seems to be made in reference to forty, 'the man who was miraculously healed was over forty years old.' More than 'forty' men were plotting against Paul in Acts 23:13. The stripes that Paul received were the generic forty minus one. Probably the clearest evidence that forty is an 'about' number is here:
for about forty years he endured their conduct in the wilderness (NIV, Acts 13:18)
I believe we should not be quick to think of forty as a (exaggerating) chiffre for quite some time to accomplish a task or achieve to endure a test. A healthy and confident person may be able to survive 40 days without food or drink e.g. under the humid and warm conditions of a cave. Is it a miracle? Life is a miracle. The number of days and months of the flood were carefully recorded. Should the forty days of rain then be a chiffre or an approximation? That does not seem quite plausible. 40 years in the wilderness and desert of Arabian Peninsula should be enough for a whole generation to die. Why should those years have been more or less than forty?
To endure hardship it helps to remember others that have experienced similar trials or such ones who have stood the same long test of time.
There is a reason there are 40s all throughout the bible just like there is a reason the number 3 is throughout all the bible, just as there is a reason the number 12 is throughout all the bible. Jesus was 40 yrs old when he died on the cross that is why there are 40s everywhere, I can easily prove this, my uncle is a baptist pastor and says Jesus died in exactly 33 AD, most scholars state Jesus was born between 7-4 BC, if Jesus was born in 7 BC and died on the cross in exactly 33 AD then that would make him exactly 40 yrs old.
Now why all of the threes ? Because Jesus died in the year 33 AD that is why.
Now why all the 12s ? Because there were 12 tribes of Israel.
And that is the 100% correct answer as to why there are forties, threes and twelves all in the bible.