Thinking like a child

Children always see things differently, and as they grow, their beliefs and values are being tuned through the influences of family, friends, social medias, books, schools and the environment - the things they see and learn, the things they experience, the life they try to adapt and get accustomed to.

Sometimes, as adults, we think too hard and at times, we are required to think out of the box. However, just going back to basics seem quite logical in some areas of our lives too, don't you think so?

Below here is an illustration of what I mean.

Apparently, the "maths" problem below is easily solved by pre-school children within 10 minutes, by programmers in an hour and needless to say, those in higher education??

I got my answer in pathetically, 45 minutes last night after thinking too hard and then tried to get back to basic and cleared my mind with complicated stuffs and started thinking like my kids. What say you? What's 2581?