câu 2:
uses crt;
var n,i: longint;
s:real;
begin
clrscr;
write ('nhap n: '); readln (n);
for i:=1 to n do
s:=s+i;
writeln ('tong la: ',s:1:3);
readln;
end.
câu 3:
uses crt;
var n,i,d: longint;
begin
clrscr;
write ('nhap n: '); readln (n);
for i:=1 to n do
begin
if i mod 2=0 then
d:=d+1;
end;
writeln ('co ',d,' so duong trong day');
readln;
end.
câu 3:
uses crt;
var n,i: longint;
t:real;
begin
clrscr;
write ('nhap n: '); readln (n);
for i:=1 to n do
t:=t+i;
writeln ('t la: ',s:1:3);
readln;
end.
