This riddle was posted to Facebook with the claim that only one in a thousand will figure it out. What do you think the answer is?

11 × 11 = 4
22 × 22 = 16
33 × 33 =?
8 + 11 = ?
It has gone viral on Facebook and the internet with millions of views as people have debated the correct answer.
Most people believe the correct answer is 36. The method to obtain the answer is to take the product of the sum of digits in each number being multiplied.

That is: aa × aa → (a + a)(a + a)
This procedure matches the pattern of the puzzle:
11 × 11 → (1 + 1)(1 + 1) = 4
22 × 22 → (2 + 2)(2 + 2) = 16
And it suggests the answer of 36.
33 × 33 → (3 + 3)(3 + 3) = 36
This “product of the sum of digits” is what many people believe to be the correct answer. But there is debate.