Hi,

One way is to use a helper column with the following formula:

=LEFT(A1,3)&"-"&RIGHT(A1,LEN(A1)-3)

then copy the helper column and paste it over the original data as values
(paste special/Values).

HTH
Jean-Guy

"cursednomore" wrote:

I have 8700 rows of numerical data, and I would like to insert a "-" as the
fourth character from the left in each cell, so that 101394 becomes 101-394,
and 1011001403 becomes 101-1001403. Any help would be greatly appreciated.