7.
var n,i,s:longint;
begin
s:=1;
write('Nhap n: '); readln(n);
for i:=1 to n do
s:=s*i;
write('s= ',s);
readln;
end.
8.
var n,s:longint;
function gt(x:longint):longint;
var kq,j:longint;
begin
kq:=1;
for j:=1 to x do
kq:=kq*j;
exit(kq);
end;
begin
write('Nhap n: '); readln(n);
for i:=1 to n do
s:=s+ gt(i);
write('s= ',s);
readln;
end.