Keyboard pressing key automatically

Hi Friends,

My product is Dell Inspiron 3542 Laptop. The 6 key in the number pad is getting pressed automatically. After I switch on laptop, in log in screen, I found that key is going pressed until I press another key. Then I have to use Backspace to remove all the entry from the password tab and type my password. The problem still persists when I am logged in. If I lock the number pad using Num Lock, then the 6 key is just Right Key and it is going pressed.

Could someone help in this matter. Thanks in advance.