I will guess your age! (UPGRADED TO 2018!)
Please don't say that the birth year gives it away. I know that it does and you don't have to remind me, and besides, the whole point is the math trick!
I didn't wan't to go this far but If it is wrong it is your mistake because this is coded to be never wrong. And think that every country has a different way of counting ages, so this one is your 'birthday count age'
I got this idea from my math teacher, she introduced the whole trick to me.
Korean version shared too.
1605 <3 s. 2017.3.20
Thanks to @Joshia_Tanumihardja for letting me know one of the bugs.