2.
program phuongt;
uses crt;
var n, i, s: integer;
begin
clrscr;
write('Nhap n = '); readln(n);
s:=0;
for i:=4 to n do s:=s+i;
write('Tong = ', s);
readln
end.
3.
program phuongt;
uses crt;
var n, i, s: integer;
begin
clrscr;
write('Nhap n = '); readln(n);
s:=0;
for i:=1 to n do s:=s+i;
write('Tong = ', s);
readln
end.
4.
program phuongt;
uses crt;
var n, i, s: integer;
begin
clrscr;
write('Nhap n = '); readln(n);
s:=0;
for i:=4 to n do if i mod 2 <> 0 then s:=s+i;
write('Tong = ', s);
readln
end.
5.
program phuongt;
uses crt;
var n, i, s: integer;
begin
clrscr;
write('Nhap n = '); readln(n);
s:=0;
for i:=5 to n do if i mod 5 = 0 then s:=s+1;
write('Co ', s, ' so chia het cho 5');
readln
end.
6.
program phuongt;
uses crt;
var n, i, s: integer;
begin
clrscr;
write('Nhap n = '); readln(n);
s:=0;
for i:=1 to n do if n mod i then s:=s+i;
write('Tong = ', s);
readln
end.
7.
program phuongt;
uses crt;
var n, i, s: integer;
begin
clrscr;
write('Nhap n = '); readln(n);
s:=0;
for i:=1 to n do if n mod i = 0 then s:=s+1;
if s=2 then write(n, ' la so nguyen to')
else
write(n, ' khong phai so nguyen to');
readln
end.
