>From the VFP5 help file...
>
>? MOD(36,10) && Displays 6
>? MOD((4*9), (90/9)) && Displays 6
>? MOD(25.250,5.0) && Displays 0.250
>
>I agree with the first two but why does the last
>one display .250 when 25.25/5=5.05?
>
>Similarly ? mod(1999,4) displays 3 instead of 75.
>
>What am I missing?

MOD() returns the remainder of the first parameter when the largest integral multiple of the second parameter less than or equal to the first parameter is subtracted from it.

MOD(36,5) = 1
SET DECIMAL TO 9
MOD(PI(),3) = 0.141592654

It does not return the non-integer portion of division by the second parameter as you speculate.