Bài 1:
program chiahetcho3;
uses crt;
var i,d:word;
begin
clrscr;
d:=0;
for i:=1 to 50 do
if i mod 3=0 then d:=d+1;
write('Tu 1 den 50 co ',d,' so chia het cho 3');
readln;
end.
Bài 2:
program songuyento;
uses crt;
var n,i,d:integer;
begin
clrscr;
write('Nhap so N can kiem tra: '); readln(n);
if n<2 then write(n,' khong phai so nguyen to')
else
begin
d:=0;
for i:=2 to n div 2 do
if n mod i=0 then d:=d+1;
if d=0 then write(n,' la so nguyen to')
else write(n,' khong phai so nguyen to');
end;
readln;
end.