Zebedee,
One way: Starting in row 2, enter the pounds in one column (A), and the ounces in another (B).
Then in a third column (C), use the formula
=SUM($A$2:A2) + INT(SUM($B$2:B2)/16)
and in a fourth column (D), use the formula
=SUM($B$2:B2) -INT(SUM($B$2:B2)/16)*16
and copy down to match your columns of data.
HTH,
Bernie
MS Excel MVP