8.

uses crt;

var i,s: integer;

begin

clrscr;

i:=1;

s:=0;

while i<=10 do

begin

s:=s+i;

i:=i+1;

end;

write(s);

readln

end.

2.

uses crt;

var i,n,s: longint;

begin

clrscr;

readln(n);

s:=1;

for i:=1 to n do s:=s*(i-1)*i;

write(s);

readln

end.

3.

uses crt;

var i,n: integer;

s: real;

begin

clrscr;

readln(n);

for i:=1 to n do s:=s+1/i;

write(s);

readln

end.

Câu 8 :

uses crt;

var i, t : longint;

begin

clrscr;

i := 1; t := 1;

while i <= 10 do

begin t := t * i;

i := i + 1; end;

write('Tich = ', t);

readln

end.

Câu 9 :

uses crt;

var i, t, n : longint;

begin

clrscr;

write('Nhap so n = '); readln(n);

t := 1;

for i := 1 to n do t := t * i;

write(n,'! = ', t);

readln

end.

Câu 10 :

uses crt;

var i, n : integer; S : real;

begin

clrscr;

write('Nhap so n = '); readln(n);

S := 0; i := 1;

while i <= n do

begin S := S + 1 / i;

i := i + 1; end;

write('S = ', S : 2 : 2);

readln

end.