I’m not sure where it came from originally. This one was posted by the prolific Cliff Pickover without credit.

The interesting thing about this problem is that, as the description says, it can be solved with only a pre-schooler’s knowledge. The apparent complexity hides a deeper simplicity that tricks a more educated person into trying all kinds of arthimetic and cyphers to solve it.

After solving it myself in about 5–10 minutes, showing just how childlike I am, I gave this problem to each of my three children: aged 19, 16, and 8.

The 19 year old gave up after seven minutes. The 16 year old persisted for about half an hour before giving up. The 8 year old took a look and, scratching her head, didn’t venture to try to solve it.

Clearly being younger wasn’t helping them solve it.

To solve it myself, I took the hint seriously: What do preschoolers know about math?

Two things: counting and how to draw numbers.

That’s all you need to solve this. I’ll put the solution at the end of the article, but this got me to think about how many important problems require, not sophisticated knowledge and advanced mathematical machinery to solve, but clear, out of the box thinking, the kind of thinking that you get from your inner child.

Psychologists use the inner child as a metaphor for the person we are when we take away all the learned behaviors of adulthood. If you are struggling with emotions, this can bring a lot of clarity because we absorb so many expectations as adults that they obscure our real needs.

But we learn a lot more as adults than how to lie to ourselves. One of the things we learn is to lean on our education in order to solve problems. In fact, school trains us to do this because the place we are most likely to face problems in math, science, engineering, and so on is school. School provides us problems to solve that teach us the material we are supposed to be learning.

I’m not sure where it came from originally. This one was posted by the prolific Cliff Pickover without credit.

The interesting thing about this problem is that, as the description says, it can be solved with only a pre-schooler’s knowledge. The apparent complexity hides a deeper simplicity that tricks a more educated person into trying all kinds of arthimetic and cyphers to solve it.

After solving it myself in about 5–10 minutes, showing just how childlike I am, I gave this problem to each of my three children: aged 19, 16, and 8.

The 19 year old gave up after seven minutes. The 16 year old persisted for about half an hour before giving up. The 8 year old took a look and, scratching her head, didn’t venture to try to solve it.

Clearly being younger wasn’t helping them solve it.

To solve it myself, I took the hint seriously: What do preschoolers know about math?

Two things: counting and how to draw numbers.

That’s all you need to solve this. I’ll put the solution at the end of the article, but this got me to think about how many important problems require, not sophisticated knowledge and advanced mathematical machinery to solve, but clear, out of the box thinking, the kind of thinking that you get from your inner child.

Psychologists use the inner child as a metaphor for the person we are when we take away all the learned behaviors of adulthood. If you are struggling with emotions, this can bring a lot of clarity because we absorb so many expectations as adults that they obscure our real needs.

But we learn a lot more as adults than how to lie to ourselves. One of the things we learn is to lean on our education in order to solve problems. In fact, school trains us to do this because the place we are most likely to face problems in math, science, engineering, and so on is school. School provides us problems to solve that teach us the material we are supposed to be learning.