B1:

Uses Crt;
Var n,i:integer; S:longint;
Begin
 Clrscr;
S:=0;
Writeln('Nhap n='); Readln(n);
For i:= 1 to n do S:=S+i;
Writeln('Vay tong cua S=',S);
Readln
End.
B2:

Uses crt;
Var n,i,s:integer;
Begin
   Clrscr;
s:=0;   

Writeln('Nhap n= '); Readln(n);
   for i:=1 to n do s:=s+2*i;
   Wrteln('Tong s =: ',s);
   Readln
End.

bai 1

var q:qword;

       n,i:longint;

begin

 writeln('nhap n');readn(n);q:=0;

for i:=1 to n do 

 q:=q+i;

writeln('tong can tinh la:',q);

readln;

end.

bai 2

var q:qword;

       n,i:longint;

begin

 writeln('nhap n');readn(n);q:=0;

for i:=1 to n do 

 q:=q+i*2;

writeln('tong can tinh la:',q);

readln;

end.

bai 3

var q1,q2:qword;  

       i,n:longint;

begin

 writeln('nhap n');readln(n);

q1:=0;q2:=0;

for i:=1 to n do

 if i mod 2=0 then q1:=q1+i

    else q2:=q2+i;

writeln('tong cac so chan:',q1);

writeln('tong cac so le:',q2);

readln;

end.

bai 4

var q:real;

       n,i:longint;

begin

 writeln('nhap n');readn(n);q:=0;

for i:=1 to n do 

 q:=q+1/i;

writeln('tong can tinh la:',q);

readln;

end.

bai 5

var q:real;

       n,i:longint;

begin

 writeln('nhap n');readn(n);q:=1;

for i:=1 to n do 

 q:=q+1/(i*(i+3));

writeln('tong can tinh la:',q);

readln;

end.