tính tổng S:

+Dùng For-to-do:

program oken;
uses crt;
var i,s: longint;
begin
        clrscr;
        for i:=1 to 100 do
                s:=s+i;
        writeln('Tong S: ',s);
        readln;
end.

+Dùng While-do:

program oken;
uses crt;
var i,n,s: longint;
begin
        clrscr;
        i:=1; s:=0;
        while i<=100 do
                begin
                        s:=s+i;
                        i:=i+1;
                end;
        writeln('Tong S: ',s);
        readln;
end.

-Tích S:

+Dùng For-to-do:

program oken;
uses crt;
var i: byte;
    s: real;
begin
        clrscr;
        s:=1;
        for i:=1 to 100 do
                s:=s*i;
        writeln('Tong S: ',s:0:0);
        readln;
end.

+Dùng while-do:

program oken;
uses crt;
var i: byte;
    s: real;
begin
        clrscr;
        i:=1; s:=1;
        while i<=100 do
                begin
                        s:=s*i;
                        i:=i+1;
                end;
        writeln('Tong S: ',s:0:0);
        readln;
end.

${Oken}$

S = 1 + 2 + ... + 100

- For ... do

uses crt;

var i, S : integer;

begin 

clrscr;

S := 0;

for i := 1 to 100 do S := S + i;

write('S = ', S);

readln

end.

- While .. do

uses crt;

var i, S : integer;

begin 

clrscr;

S := 0; i := 1;

while i <= 100 do begin

S := S + i; i := i + 1; end;

write('S = ', S);

readln

end.

- S = 1 x 2 x ... x 100

- For ... do

uses crt;

var i : byte; S : real;

begin 

clrscr;

S := 1;

for i := 1 to 100 do S := S * i;

write('S = ', S : 100 : 0);

readln

end.

- While .. do

uses crt;

var i : byte; S : real;

begin 

clrscr;

S := 1; i := 1;

while i <= 100 do begin

S := S * i; i := i + 1; end;

write('S = ', S : 100 : 0);

readln

end.