When the date in B4 equals the start date, DATEDIF returns zero.
On the next month, DATEDIF returns 1, and so on.
This effectively starts the numbering pattern at 3 instead of zero.
For example, MOD(10,3) = 1.
The result of MOD carries the same sign as the divisor.
The DATEDIF (Date + Dif) function is a “compatibility” function that comes from Lotus 1-2-3.
Excel won’t help you fill out the arguments for DATEDIF like other functions, but it will work…
