If you use Facebook you will have seen puzzles like the one below. You have to identify the rule that produces the answers in the first 3 lines, and use it to find the result of the fourth line.

ONLY FOR GENIUSES CLICKBAIT
1 + 4 = 5
2 + 5 = 12
3 + 6 = 21
8 + 11 = ?

However, there are AT LEAST 3 rules that will give correct results for the first 3 lines above, and each gives a different (valid) answer to the 4th line.

How many can you get? You may be able to identify 2 answers, but can you identify three?

All 3 answers involve mathematical solutions. Two of these answers regularly appeared in the replies to the original puzzle. I didn’t see the 3rd although I’m sure it will appear somewhere amongst the 200K+ replies. This is a blog about contrarian thinking, and for the 3rd solution you will need to approach the problem from a different direction.

Click here to reveal Answers and Explanations
1 + 4 = 5
2 + 5 = 12
3 + 6 = 21
8 + 11 = ?

Answer = 96. Rule: multiply the first and second numbers then add the first number.
So “8 + 11” = 8 X 11 + 8 = 96

Answer = 40. Rule: add the 2 numbers, then add the result from the previous line

3 + 6 = 21
8 + 11 = ?
i.e. 8 + 11 + 21 = 40

Answer 201:

The previous answers involved “left side” thinking, you now need to use contrarian “right side” thinking:

1 + 4 = 5 = 5
2 + 5 = 7 = 12
3 + 6 = 9 = 21
8 + 11 = 19 = ?
i.e. the sums on the left are exactly what they appear to be (“2 + 5” really does mean “2 plus 5”) and what we need is a rule for how the results of the sums are represented on the right side.
 
In computing (denary) “3” might be represented in Base 2 as “11”, likewise in Quiz Land we can create a rule to represent our results in different Bases. (Online Number Base Calculator here )

1 + 4 = 5 (result represented in Base 6)
2 + 5 = 12 (Base 5)
3 + 6 = 21 (Base 4)
8 + 11 = 201 (Base 3)

So in quiz land our rule is to represent the answer in a Number Base one lower than the previous answer.

You may have found more answers, if so please post them with your explanation in the comments below.

Credits: the original puzzle was posted on FB by Asap Alee. You can see his other puzzles by viewing his Photos (and if you really want you click his image for this puzzle and check out the 200K answers on FB). Looking at the “skill level” required for his other puzzles, I assume he intended the answer to be the first or second answer above.