I means I can put any function in some Column so that when the corresponding
column data changes, the column would automaticall exceute column function.
not only about tax.

such as
I put function "=year(now)-left(a1,4)" in Col B, it would work in whole
Column
Col:A Col:B
1 1980-9-1 27
2 1983-11-2 24
.........................
X Row (I am not sure where it is)
X 1979-8-2 28
........................

hui