Ken wrote...
I have a spreadsheet that is 8 columns by 1000 rows. each cell contains
a number from 1 to 100. I need to find out which numbers in each column
repeat the most often, then the next most frequent.
....

If your data were in A3:H1002, and you wanted the most frequent values
in row 1005 (so most frequent in A3:A1002 in A1005, etc.), next most
frequent values in row 1006, etc., try these formulas.

A1005:
=MODE(A$3:A$1002)

A1006 [array formula]:
=MODE(IF(COUNTIF(A$1005:A1005,A$3:A$1002)=0,A$3:A$ 1002))

Fill A1005:A1006 right into B1005:H1006. If you want 3rd most frequent
values in row 1007, select A1006:H1006 and fill down into A1007:H1007.