Experts,
MeritNation


Once a teacher of my school,asked me to tell a 3 or 4 or 5 digit number to him, he then asked me to multiply it with another 3 or  4 or 5 or 6 digit number and asked me to tell that to him after I would take out the product of the two numbers. Then he asked me to say the product in which all the digits would be there in there own places and only one digit I would not tell him which would be told as a (*) and will be hidden. And he in just a matter of 5 seconds, he told the missing digit. How we perform this trick? What is the trick behind this? Explain it with 2 examples.  PLEASE... 

LIKE: If "2465 x 5426 = 133750*0" and my teacher told me the the digit in place of the star symbol in just five seconds. HOW?

{I know that this is not related to the course at all, but for a general knowledge which would help me in olympiads... so I asked this and want to know this PLEASE...}