Here is one of those math tricks that has been floating around the Internet. Don’t cheat by scrolling down! It takes less than a minute. At the end, I will provide an explanation of how this trick is done.
Follow these instructions, and I will guess your age by chocolate:
Step 1: Pick the number of times a week that you like to eat chocolate (more than once but less than 10).  
Step 2: Multiply this number by 2 (just to be bold)! 

Step 3: Add 5 to the total. 

Step 4: Multiply your total by 50 — I’ll wait while you get a calculator. 

Step 5: If you have already had your birthday this year, add 1759. If you haven’t, then add 1758. 

Step 6: Now subtract the four digit year that you were born. 

Your result should be a three digit number. The first digit is your original number (i.e., how many times you want to have chocolate each week). The next two numbers are your age! 
This is the only year (2009) that this trick will work, so spread it around!
How to Solve this Trick
This is a simple algebra math trick. For test purposes, let’s assume you were born on January 1, 1970. That would make your age 39 (as of today, July 9, 2009). So, following the steps above:
 Pick the number of times a week that you like to eat chocolate. So let’s assign the variable “C” for chocolate:
= C
 Multiply this number by 2. So that’s:
= C x 2
 Add 5 to the total.
= (C x 2) + 5
 Multiply your total by 50.
= ((C x 2) + 5) x 50
= (C x 2 x 50) + (5 x 50)
= (C x 100) + 250
 If you have already had your birthday this year (which we have, using our test birthday of January 1), add 1759.
= ((C x 100) + 250) + 1759
= (C x 100) + 2009 (which is the current year!)
 Subtract the four year digit you were born.
= (C x 100) + 2009 – 1970
= (C x 100) + 39 (which is our test age!)
= C39
The final result is a three digit number. The first digit is your original number “C” (C x 100). The next two numbers are your age (39).
So the trick is to take your original number and multiply it by 100 so that it’s the first digit in the result. Next, it multiplies and adds some numbers that equal the current year. So then if you subtract the year you were born, the result is the number of years you have been alive, i.e., your age.
SOLVED!
If you enjoyed this puzzle, be sure to check out the Regifting Robin Mind Trick.
Article published on July 9, 2009
If you like this article, please share it: 
July 25th, 2009 at 9:20 pm
Tried 3 times and didn’t work for me – number was 5 digits long.
December 1st, 2009 at 2:19 pm
ACE I DID IT IN MY MATHS LESSON 2DAY A TRIED IT ON MY MUM AND DAD IT IS THE GREASTING THING I HAVE EVER SEEN!!!!!!! <3
December 23rd, 2009 at 2:22 pm
this is so cool how do u do it
March 6th, 2010 at 10:42 pm
That is so cool. It worked everytime. And, Freya, it says how to do it!
September 1st, 2010 at 7:07 am
hahahahahahahahahahaha it doesn’t work me and April tried it it said we were 11 in fact people we are 12 hahahahahahahahahaha RUBBISH !!!!!!!!
December 20th, 2010 at 9:33 am
It does not work it said i was 11 when i am twelve!
December 21st, 2010 at 1:40 am
I am 12 not 11!
February 18th, 2011 at 5:09 pm
[…] Guess Your Age by Chocolate devtopics.com […]
March 30th, 2011 at 1:29 pm
it said i was 12, im 14 :L
April 1st, 2011 at 10:20 am
my number was 16….I’m 18… and i dont eat chockolate
October 6th, 2011 at 8:33 am
Why do I always see these “It didn’t work I’m x+1 or x+2 years old” .. read where it says it ONLY WORKS for 2009!! (or add 2 for 2011 to the equation and it will work)