1.

program Tin_hoc;

uses crt;

var N,i:integer;

      tong:real;

begin

clrscr;

write('Nhap N<=1000: ');readln(N);

while N>1000 do 

begin

 write('Nhap lai: ');

 readln(N);

end;

tong:=0;

for i:= 1 to N do tong := tong + (i/(i+1));

writeln('Tong=',tong:0:2);

readln;

end.

2. 

program Tin_hoc;

uses crt;

var N,i,k:integer;

a:array [1..10000] of integer;

begin

clrscr;

writeln('Nhap N<=10000:');readln(N);

while N>1000 do 

begin

 write('Nhap lai: ');

 readln(N);

end;

writeln('Nhap ',N,' so cua day:');

for i:=1 to N do readln(a[i]);

for i:= 1 to N do write(a[i],'  ');writeln;

k:=0;

for i:= 1 to N do if a[i] = a[N+1-i] then inc(k);

if k=N do writeln('Day tren doi xung') else writeln('Day tren khong doi xung');

readln;

end.

3.

program Tin_hoc;

uses crt;

var i,k,j:integer;

      s,s2: string;

begin

clrscr;

writeln('Nhap Ho va Ten:');readln(s);

i:=length(s);

while ord(s[i]) = 32 then i:=i-1;

k:=length(s) - i;

s2:= copy(s,k,i+1);

writeln('Ten: ',s2);

readln;

end.

4. 

program Tin_hoc;

uses crt;

var i,N,tong,j,k:longint;

begin

clrscr;

writeln('Nhap N<=1000000000');readln(N);

while N>1000000000 do 

begin

 write('Nhap lai: ');

 readln(N);

end;

tong:=0;

for i:= 2 to N do if N mod i = 0 then do

begin

k:=0;

for j:= 1 to i do if i mod j = 0 then k:=k+1;

if k=2 then tong:=tong+i

end;

writeln('Tong cac uoc nguyen to cua ',N,' la: ',tong);

readln;

end.

Mik không biết làm câu 2b nên bạn thông cảm. Còn bạn chạy thử chỗ nào sai kêu mik mik sửa cho( Nhớ chụp màn hình lại để mik biết lỗi j nha)