Can you find out which number multiplied by itself will give the output as 12345678987654321?

Replace the question mark with the number below given a simple math problem.

A detective visits his friend John just to discover that John's neighbour Dr Jacob was murdered. Dr Jacob, who is a mathematician wrote the murderer's name in a code word "Hcqtfz". There were five suspects
1. Ajit
2. Pankaj
3. Ganpat
4. Deenu
5. Hariya

The Detective was instantly able to find the murderer.
Can you?

Which tank will fill first?

The world's largest Thanksgiving turkey was on display at a fair. Everyone was admiring it when suddenly a woman ran up and shot the turkey and left. Everyone knew her yet nobody made any attempts to stop or report her. Why?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

A quarter is one-fourth of a dollar but Mr. John has changed the equation as below :

DOLLAR * 4 = QUARTER

Can you replace each letter with a digit to make the above solution correct?

Accidentally, two trains are running in the opposite direction and enter a tunnel that is 200 miles long. A supersonic bird that has fled the lab and taken shelter in the tunnel starts flying from one train towards the other at a speed of 1000 mph. As soon as it reaches the second train, he starts flying back to avoid collision and meets the first train again at the other end. The bird keeps flying to and fro till the trains collide with each other.

What is the total distance that the supersonic bird has traveled till the trains collided?

using four eights (8) and a one (1) and one mathematical symbol , create the number 100

Dr Doom invited a group of puzzle fanatics to a party which was oriented toward having puzzle-oriented games. At night, he introduced the guests to a 'unique riddle'. A prize was offered to the one who solved it first.

The guests included six people named Tom Paul, Fox Obama, Jeremy Reener, Alex Murphy, Prim Pastor, and Ellen Page. The winner of the 'unique riddle' contest was to be announced after the dinner. So Dr. Doom stood up and started the announcement:

'Okay now everybody!'
'The winner of�'
'The Hardest Riddle Ever Event'

But before he could complete it, the light went out and his voice was not heard without the mic by anyone. But they already knew who the winner was. Can you deduce the name of the winner?