Mình làm cả 5 bài luôn, cho mình xin hay nhất.

100% đúng nha.

Bài 1: 

uses crt;
var k,t:longint;
begin
clrscr;
   write('Nhap so kw: ');readln(k);
   if k>=100 then inc(t,100000) else inc(t,1000*k);
   if k>=200 then inc(t,200000) else inc(t,2000*(k-100));
   if k>200 then inc(t,3000*(k-200));
   writeln('So tien: ',t);
readln
end.

Bài 2: 

uses crt;
var tbm:byte;
begin
clrscr;
   write('Nhap trung binh mon: ');readln(tbm);
   write('Xep loai: ');
   if tbm>=8 then write('Gioi') else
   if tbm>=6.5 then write('Kha') else
   if tbm>=5 then write('TrungBinh') else
   write('Yeu');
readln
end.

Bài 3:

uses crt;

var a,b:longint;
begin
clrscr;
   write('Nhap 2 so duong: ');readln(a,b);
   while a<>b do if b>a then b:=b-a else a:=a-b;
   writeln('Uoc chung lon nhat: ',a);
readln
end.

Bài 4: 

uses crt;
var t,i,n:longint;
begin
clrscr;
   write('Nhap n: ');readln(n);
   t:=1;
   for i:=2 to n do t:=t+t*i;
   writeln('Tong: ',t);
readln
end.

Bài 5:

uses crt;
var i:longint; n,a:real;
begin
clrscr;
   write('Nhap so thuc a: ');readln(a);
   while n<=a do
      begin
         inc(i);
         n:=n+1/i;
      end;
   writeln('n= ',n:0:2);
readln
end.

Bài 1:

program tiendien;

uses crt;

var kw:integer;

      tien:longint;

begin

     clrscr;

     write('Nhap so kw: ');   readln(kw);

     if kw>=100 then tien:=100*1000

         else tien:=kw*1000;

     kw:=kw-100;

     if kw>=200 then tien:=tien+100*2000

         else if kw>0 then tien:=tien+kw*2000;

     kw:=kw-100;

     tien:=tien+kw*3000;

     write('So tien dien phai tra la: ,tien);

     readln;

end.

Bài 2:

program xeploaij;

var dtb:real;

begin

     clrscr;

     write('Nhap diem trung binh: ');     readln(dtb);

     if dtb>=8 then write('Gioi');

     if (dtb<8) and (dtb>=6.5) then write('Kha');

     if (dtb<6.5) and (dtb>=5) then write('Trung binh');

     if (dtb<5) then write('Yeu');

     readln;

end.

Bài 3:

program UCLN;

uses crt;

var a,b:integer;

begin

     clrscr;

     write('Nhap so thu nhat: ');     readln(a);

     write('Nhap so thu hai: ');      readln(b);

     abs(a); abs(b);

     while a<>b do

          if a>b then a:=a-b else b:=b-a;

     write('UCLN la: ',a);

     readln;

end.

Bài 4:

program tinhtong;

uses crt;

var n,i,j:integer;

      S,t:longint;

begin

     clrscr;

     write('Nhap n: ');   readln(n);

     S:=0;

     for i:=1 to n do

          begin

               t:=1;     

               for j:=1 to i do

                    t:=t*j;

               S:=S+t;

          end;

     write('S= ',s);

     readln;

end.