1/
Program BTH;
uses crt;
var s,n,i:longint;
Begin
clrscr;
write('Nhap n: ');readln(n);
For i:=1 to n do
Begin
s:=s+i;
end;
Writeln('Tong day so tren la: ',s);
readln;
end.
2/
Program BTH;
uses crt;
var s,n,i:longint;
Begin
clrscr;
write('Nhap n: ');readln(n);
For i:=1 to n do
Begin
s:=s+i*i;
end;
Writeln('Tong day so tren la: ',s);
readln;
end.
3/
Program BTH;
uses crt;
var s,n,i:longint;
Begin
clrscr;
write('Nhap n: ');readln(n);
For i:=1 to n-1 do
Begin
if i mod 2=0 then
s:=s+i;
end;
Writeln('Tong day so tren la: ',s);
readln;
end.
