FORTY has long been universally recognized as an important number, both on account of the frequency of its occurrence, and the uniformity of its association with a period of probation, trial, and chastisement—(not judgment, like the number 9, which stands in connection with the punishment of enemies, but the chastisement of sons, and of a covenant people). It is the product of 5 and 8, and points to the action of grace (5), leading to and ending in revival and renewal (8). This is certainly the case where forty relates to a period of evident probation. But where it relates to enlarged dominion, or to renewed or extended rule, then it does so in virtue of its factors 4 and 10, and in harmony with their signification.
There are 15 such periods which appear on the surface of the Scriptures, and which may be thus classified:—
Forty Years of Probation by Trial:
Forty Years of Probation by Humiliation and Servitude:
FORTY DAYS - There are eight of such great periods on the surface of the Bible:
* Thus 40 becomes a number closely connected with Judah, as 390 (Eze 4:5) is the number of separated Israel. The significance of this will be seen (on p. 215), for 40 is a multiple of 8, and 390 is a multiple of 13. It may also be noted that 65 (5x13) is the number of Ephraim, while 70 is specially connected with Jerusalem.
Here is a link to the source of this information, an online version of E.W. Bullinger's book Number in Scripture