You probably try to figure out what you are looking at as quickly as possible when you look at something. Human nature is to take in as much information as possible and then move on to something else.
We also do this in order to protect ourselves. When we glance at something, we start to assess it. If something is wrong that could hurt us or others, it may trigger the fight or flight response.
As you look at the following picture, however, you probably just think it is a series of stripes, and you may not think anything else about it. However, it contains a two-digit number. Do you know where it is?
Find the two-digit number
Do you still have trouble finding the number? Back away from your computer screen or phone. Putting some distance between yourself and what you are looking at is sometimes helpful.
Another thing that sometimes works is scrolling up and down quickly.
Are you still having trouble seeing it?
It is 17