First gather your supplies
Before you preform your magic trick to your friend, write down todays year x2! So for example 2x2012=4024
Now seal your piece of paper in the envelope...
Now get your friend to write down the year they were born, a important year for them, how many years since that important year, and the age they are turning this year!
Now get them add up all their numbers to get to the total, if you want you can use a calculator to make it easier!
Now open the envelope and let them be amazed😳...😄