Bài 1 :

Program BT_1;
Var n,dem,i,j,t,d : longint;
Begin
repeat
Write ('Nhap N : ');Readln(n);
until n > 0 ;
dem := 0;
t := 0;
i := 0;
d := 0;
While dem <> n do
Begin
i := i + 1;
For j := 1 to i do If i mod j = 0 then d := d+ 1;
If d = 2 then
Begin
t := t + i;
dem := dem + 1;
end;
d := 0;
end;
Writeln('1.Tong cua ',n,' so nguyen to la : ',t);
end.

Bài 2 : 

Program BT_2;
Var n,i,t : longint;
    a : array [1..100] of longint;
Begin
repeat
Write ('Nhap N : ');Readln(n);
until n > 0 ;
t := 0;
For i := 1 to n do
Begin
Write ('A[',i,']= ');Readln(A[i]);
If a[i] mod 3 = 0 then t := t + a[i];
end;
Write ('2.Tong cac so chia het cho 3 la : ',t);
end.

Bài 3 : 

Program BT_3;
Var n,i,max : longint;
    a : array [1..100] of longint;
Begin
repeat
Write ('Nhap N : ');Readln(n);
until n > 0 ;
For i := 1 to n do
Begin
Write ('A[',i,']= ');Readln(A[i]);
end;
max := a[1];
For i := 1 to n do If A[i] > max then max := A[i];
Write ('3.Max la : ',max);
end.

Câu 1:

uses crt;
var n,i,d,s,s1:longint; a:array[1..1000000]of longint;
function nt(a:longint):boolean;
var i:longint;
begin
   i:=2;
   while(a>1)and(a mod i<>0)do inc(i);
   nt:=i=a;
end;
begin
clrscr;
   readln(n);
   for i:=1 to n do 
      begin
         read(a[i]);
         inc(s,a[i]);
      end;
   writeln('Tong: ',s);
   for i:=1 to n do 
      if nt(a[i]) then 
         begin
            inc(d);
            inc(s1,a[i]);
         end;
   writeln('Co ',d,' so nguyen to');
   writeln('Tong so nguyen to: ',s1);
readln
end.

Câu 2:

uses crt;
var n,i,s:longint; a:array[1..1000000]of longint;
begin
clrscr;
   readln(n);
   for i:=1 to n do 
      begin
         read(a[i]);
         if a[i] mod 3=0 then inc(s,a[i]);
      end;
   writeln(s);
readln
end.

Câu 3:

uses crt;
var n,i,s,max:longint; a:array[1..1000000]of longint;
begin
clrscr;
   readln(n);
   max:=a[1];
   for i:=1 to n do 
      begin
         read(a[i]);
         if a[i]>max then max:=a[i];
      end;
   writeln(max);
readln
end.