They say that only one in 1,000 people can figure out the second possible answer to the test, so can you?
SOLUTION 1
The makers explain that most people will begin by adding 1 + 4 to reach the answer 5.
Then they'll add 2 + 5 to the sum of 5 to get an answer of 12.
The majority of users will use the same process in the next line, adding 3 + 6 to get 9, then add nine to the sum in the equation above (12) to reach the figure 21.
In the last stage, they will add 8 + 11 to get 19, before adding it to the sum of the previous line (21) to get 40.
While makers say that 40 is a widely accepted and correct answer, there's another answer - and only a select few will reach it.
SOLUTION 2
While makers say that, of course, 1 + 4 = 5, intelligent people will get the answer by adding 1 to 4 x 1.
Using that formula, they'll add 2 to 2 x 5 to get 12.
They'll then add 3 to 6 x 3 to get 21.
And to reach the final and alternate answer, they'll add 8 to 11 x 8 to get 96.