Questions

Here in the given number puzzle, the given numbers follows a pattern that 

1 + 4 = 5 => 1 x 4 + 1 = 4 + 1 = 5 

2 + 5 = 12 => 2 x 5 + 2 = 10 + 2 = 12   

3 + 6 = 21 => 3 x 6 + 3 = 18 + 3 = 21 

Similarly, 

8 + 11 = 96 => 8 x 11 + 8 = 88 + 8 = 96  

Hence, the missing number in the given number puzzle is 96.

When a candidate is officially nominated at the national convention, then the presidential campaign begins.

The title of Father of the Nation was given to Mohan Das Karamchand Gandhi known as Mahathma Gandhi by Netaji Subhas Chandra Bose.

He was the first who addressed Mahatma Gandhi as Father of the Nation on Singapore Radio on July 6, 1944.

Saraswat Bank, the largest lender in the co-operative space, has appointed Smita Sandhane as its Managing Director (MD). She is the first woman chief of India's largest urban co-operative bank.
'Service to the common man' is the Motto of Saraswat Bank.

A measuring device.

Measuring devices have feet on them to measure distance.

You will get the answer in the riddle itself, if you read the riddle carefully.

The riddle says "A cowboy arrives in town on Friday." So Friday is the name of the horse on which he comes. Hence, the only possibility is he arrives on the horse friday on Tuesday, stays for 3 days and leaves on the same horse on Friday.