What is the mathematical explanation for this trick? I found the following method to find one's age. It is working exactly for my case. I like to understand and solve this puzzle. If this is wrong forum, my sincere apologies. Please guide me solve this.


*

*Take last digit of your mobile number 

*Multiply it by 2

*Add 5 with the above answer

*Multiply the answer with 50

*Add 1764 with the answer

*Subtract the your birth year from the result in part 5 (example 1985, 1973, etc.)


Now you will get 3 digit number. The first one is last digit of your mobile number, last two digits are your age.

That's elementary. If $d$ is the last digit and $y$ your birth year, you are computing
$$(2d+1)50+1964-y=100d+2014-y.$$
The first term is the digit shifted two positions to the left (times $100$); the other two terms compute your age.
You'll have to increment the constant $1964$ every year, and the trick won't work for centenarians.
