>VFP doesn't handle numbers greater than 16 digits of precision (left and right of decimal point). It rounds from there.
>
>Check out the Help
>Visual FoxPro Documentation - Using Visual FoxPro - Programmer's Guide - Appendix - Visual FoxPro System Capacities - Digits of Precision in Numeric Computations

Or, more helpfully (IMNSHO), Q259562 INFO: The Visual FoxPro Digits of Precision.