Bài 2: 

uses crt;

var x,i,n,dem:integer;

begin

clrscr;

readln(n);

dem:=0;

for i:=1 to n do 

begin

readln(x);

if x mod 2=0 then inc(dem);

end;

writeln(dem);

readln;

end.

Câu 1: 

uses crt;

var a:array[1..100]of integer;

i,n,t,s:integer;

begin

clrscr;

write('Nhap n='); readln(n);

for i:=1 to n do 

  begin

write('A[',i,']='); readln(a[i]);

end;

t:=0;

s:=1;

dem:=0;

for i:=1 to n do 

  if a[i] mod 3=0 then 

begin

inc(dem);

t:=t+a[i];

s:=s*a[i];

end;

if dem=0 then writeln('Khong co so chia het cho 3 trong day')

else begin

writeln('Tong cac so chia het cho 3 la: ',t);

writeln('Tich cac so chia het cho 3 la: ',s);

end;

readln;

end.

Câu 2: 

uses crt;

var a:array[1..100]of integer;

i,n,dem,t:integer;

begin

clrscr;

write('Nhap n='); readln(n);

for i:=1 to n do 

  begin

write('A[',i,']='); readln(a[i]);

end;

dem:=0;

t:=0;

for i:=1 to n do 

 if a[i] mod 2=0 then 

begin

inc(dem);

t:=t+a[i];

end;

writeln('So so chan la: ',dem);

writeln('Tong cac so chan la: ',t);

readln;

end.

Câu 3: 

uses crt;

var a:array[1..100]of integer;

i,n,dem1,dem2,t1,t2,s1,s2:integer;

begin

clrscr;

write('Nhap n='); readln(n);

for i:=1 to n do 

  begin

write('A[',i,']='); readln(a[i]);

end;

dem1:=0;

dem2:=0;

t1:=0;

t2:=0;

s1:=1;

s2:=1;

for i:=1 to n do

begin

if a[i] mod 2=0 then 

begin

inc(dem1);

t1:=t1+a[i];

s1:=s1*a[i];

end

else begin

inc(dem2);

t2:=t2+a[i];

s2:=s2*a[i];

end;

end;

if dem1=0 then writeln('Khong co so chan trong day')

else begin

writeln('So so chan la: ',dem1);

writeln('Tong cac so chan la: ',t1);

writeln('Tich cac so chan la: ',s1);

end;

if dem2=0 then writeln('Khong co so le trong day')

else begin

writeln('So so le la: ',dem2);

writeln('Tong cac so le la: ',t2);

writeln('Tich cac so le la: ',s2);

end;

readln;

end.

#include <bits/stdc++.h>

using namespace std;

int B[100],n,t;

{

cin>>n;

for (int i=1; i<=n; i++) cin>>B[i];

t=0;

for (int i=1; i<=n; i++)

if (B[i]%10==0) t+=B[i];

cout<<t<<endl;

int dem=0;

for (int i=1; i<=n; i++)

if ((i%2==0) && (A[i]%2!=0)) dem++;

cout<<dem<<endl;

for (int i=1; i<=n; i++)

if ((A[i]%2!=0) && (A[i]%3==0)) cout<<A[i];

}

program BaiToanMang;

var
  A: array[1..100] of integer;
  N, i, demChan, tongLeChia3: integer;

begin
  write('Nhap so phan tu cua mang: ');
  readln(N);
  writeln('Nhap cac phan tu cua mang: ');
  for i := 1 to N do
  begin
    write('a[', i, ']= ');
    readln(A[i]);
  end;
  tongLeChia3 := 0;
  for i := 1 to N do
  begin
    if (A[i] mod 2 = 1) and (A[i] mod 3 = 0) then
    begin
      tongLeChia3 := tongLeChia3 + A[i];
    end;
  end;
  writeln('Tong cac so le chia het cho 3: ', tongLeChia3);
  demChan := 0;
  for i := 2 to N do
  begin
    if (A[i] mod 2 = 0) and (i mod 2 = 1) then
    begin
      demChan := demChan + 1;
    end;
  end;
  writeln('So phan tu chan o vi tri le: ', demChan);
  writeln('Cac so chan chia het cho 5: ');
  for i := 1 to N do
  begin
    if (A[i] mod 2 = 0) and (A[i] mod 5 = 0) then
    begin
      write(A[i], ' ');
    end;
  end;
end.

ko bt đúng ko ko dùng pascal nhiều

b dùng pascal hay python V:

Viết chương trình tính tổng các số chẵn từ 1->n

Uses CRT;

Var i,n,s:integer;

Begin clrscr;

Write('Nhap so n= ');Readln(n);

S:=0;

For i:=1 to n do

If i mod 2 = 0 do S:=S+i;

Writeln;

Write('tong cac so chan la ',S);

Readln;

End.

Viết chương trình tính tổng các số lẻ từ 1->n

program bai1;

var s,i,n:longint;

begin write('N= ');

readln(n); s:=0;

for i:=1 to n do if i mod 2<>0 then s:=s+i;

write('s= ',s);

readln

end.

Chúc em học tốt

Program tinhtong;
uses crt;
var i, SUM, N : integer;
Begin
Clrscr;
Write('Nhap N: '); Readln(n);
SUM := 0; For i:=1 to N do if (i mod 3 = 0) then SUM:= SUM + i;
Write('Tong la: ', SUM);
Readln;
End.

(3+6+9+12+18+21+27+33+36+42+45+48+52+54+60+63+66++69+72+75+78+81+84+87+90+93+96+99)⋮3

#include <bits/stdc++.h>

using namespace std;

int t,i;

int main()

{

t=0;

for (i=1; i<=100; i++)

if (i%3==0) t=t+i;

cout<<t;

return 0;

}