Children aged between 4 and 6 can solve this problem in less than 5 minutes. Can you?
Okay here's the answer
The answer is 2. For each number count the number of circles present in the letters. Adult brains tend see what the numbers represent, an equation, and so we look for a mathematical solution. Those not yet trained to recognise the sequence as an equation do not limit their search for a solution and begin to evaluate the pattern visually. Interestingly in brain teasers like this people with ADHD and other neurological impairments tend to perform better.