J.H. wrote...
I have a question on the funtion "MOD". When the number to be divided is more
than nine digits (like: 1,234,457,890), the funtion would return error. How
can I fix this?

As others have pointed out, Excel's MOD function is flawed compared to
what the hardware is capable of calculating. Instead of MOD(a,b) calls,
use (a-b*int(a/b)).