Answers

1. 0

= (x-a)(x-b)(x-c)...(x-x)(x-y)(x-z)  

= (x-a)(x-b)(x-c)...0 x (x-y)(x-z)   

= 0 

2. 11(All the months except February have 30 days.)

          3. Independence Day (August 15 ) We all share the same day)