Cách 1 dùng lệnh for do:
Uses crt;
var i,n,k: integer;
begin clrcsr;
readln(n);
for i:=1 to n do begin
if(i mod 2=0) and (i>=10) then k:=k*i;
end;
writeln(k);
readln;
end.
Cách 2 dùng lệnh while do
Uses crt;
var m,n,o: integer;
begin clrcsr;
readln(n);
o:=1;
m:=1;
while (m<n) do begin
m:=m+1;
if(m mod 2=0) and (m>=10) then o:=o*m;
end;
writeln(o);
readln;
end.