I think you should isolate the numbers first and then use the towords function:
stringvar array x := split({table.memo}," ");
numbervar i;
numbervar j := ubound(x);
stringvar y := "";
for i := 1 to j do(
if not isnumeric(x) then
y := y + x+" " else
if isnumeric(x then
y := y + towords(tonumber(x),1)+" "
);
y
...where the 1 in the towords function indicates the number of decimals--although the decimals are expressed as a fraction like this: .5 becomes 5/10 or 50/100 if you set it to "2".
-LB