Here is a mind-reading trick which will enable you to discover a person’s age. Ask a friend to:
multiply his age by 2
multiply the result by 50
add the age of his father
subtract the number of days in a year
When he/she gives you the result, you will tell him his age and that of his father.
How to do it: Add 115 to the number you get. The first two numbers will represent your friend’s age, the last two is his father’s age.