All types of content are shared on social networks and many of them go viral, such as mental challengesand in the last few hours a riddle is giving a lot to talk about and tell.
This is the image of a blackboard on which a series of numbers are written in a row from top to bottom and the challenge is to find all the numbers that is in it, from zero to nine.
TO simple view You can see that in the photograph there are three numbers drawn on the blackboard: six, nine and four.
However, if you look closely, the lines drawn on the blackboard hide other numbers like two, eight or one.
