1 uses crt;

var i,t,n,k:integer;

begin

clrscr;

t:=0;k:=1;

readln(n);

for i:=1 to n do if i mod 3 =0 then 

begin

k:=k*i;

t:=t+i;

end;

readln;writeln(t,k);

end.

2

uses crt;

var i,t,n:integer;

begin

clrscr;

t:=0;

readln(n);

for i:=1 to n do if i mod 2 =0 then 

t:=t+i;

readln;writeln(t);

end.

3

so chẵn:

uses crt;

var i,t,n,k:integer;

begin

clrscr;

t:=0;k:=1;

readln(n);

for i:=1 to n do if i mod 2 =0 then 

begin

k:=k*i;

t:=t+i;

end;

readln;writeln(t,k);

end.

số lẻ:

uses crt;

var i,t,n,k:integer;

begin

clrscr;

t:=0;k:=1;

readln(n);

for i:=1 to n do if i mod 2 <>0 then 

begin

k:=k*i;

t:=t+i;

end;

readln;writeln(t,k);

end.

Câu 1:

uses crt;
var n,i,s:longint;
begin
      clrscr;
      write('Nhap n: '); readln(n);
      for i:=1 to n do if i mod 3 = 0 then inc(s,i);
      writeln('Tong: ',s);
      readln
end.

Câu 2:

uses crt;
var n,i,s,d:longint;
begin
      clrscr;
      write('Nhap n: '); readln(n);
      for i:=0 to n do if i mod 2 = 0 then begin
            inc(d);
            inc(s,i);
      end;
      writeln('Co ',d,' so chan');
      writeln('Tong: ',s);
      readln
end.

Câu 3:

uses crt;
var n,i,s,d,d1,sl:longint;
begin
      clrscr;
      write('Nhap n: '); readln(n);
      for i:=0 to n do if i mod 2 = 0 then begin
            inc(d);
            inc(s,i)
      end
      else begin
            inc(d1);
            inc(sl,i);
      end;
      writeln('Co ',d,' so chan');
      writeln('Co ',d1,' so le');
      writeln('Tong chan: ',s);
      writeln('Tong le: ',sl);
      readln
end.