Change it to:
if remainder({table.no},10) = 1 and
{table.no} <> 11 then
totext({table.no},0,"")+"st" else
if remainder({table.no},10) = 2 and
{table.no} <> 12 then
totext({table.no},0,"")+"nd" else
if remainder({table.no},10) = 3 and
{table.no} <> 13 then
totext({table.no},0,"")+"rd" else
totext({table.no},0,"")+"th"
-LB