*Câu 1:
program b1;
uses crt;
var i,t,s,n,k,l:longint;
a:array[1..100000] of longint;
begin
clrscr;
write('Nhap n:');readln(n);
for i:=1 to n do
begin
write('a[',i,']=');readln(a[i]);
end;
s:=0;
k:=0;
for i:=1 to n do
if a[i]>5 then
begin
k:=k+1;
s:=s+a[i];
end;
t:=0;
l:=0;
for i:=1 to n do
if a[i]<15 then
begin
l:=l+1;
t:=t+a[i];
end;
writeln('Co ',k,' so lon hon 5');
writeln('Tong cac so lon hon 5: ',s);
writeln('Co ',l,' so be hon 15');
writeln('Tong cac so be hon 15: ',t);
readln
end.
*Cau 2:
program b2;
uses crt;
var i:longint;
s:string;
begin
clrscr;
write('Nhap xau:');readln(s);
for i:=1 to length(s) do
if s[i] in ['0'..'9'] then delete(s,i,1);
writeln('Xau sau khi bo cac ky tu so:',s);
readln
end;
*Cau 3:
program b3;
uses crt;
var a,b,c,d:longint;
begin
clrscr;
writeln('Cac so thoa he thuc la:');
for a:=1 to 9 do
for b:=0 to 9 do
for c:=0 to 9 do
for d:=0 to 9 do
if 1000*a+100*b+10*c+d=(10*a+b+10*c+d)*(10*a+b+10*c+d) then write(a,b,c,d,' ');
readln
end.
---- Ok rồi đó bạn -------
------- Good luck --------