A math puzzle has the internet scratching its head.
If you take the plus sign literally, the equations appear to be incorrect, so the answer isn’t 19.
However, if you interpret the equations a little differently, a consistent pattern emerges.
One way of interpreting the equations is that they just run on, so that the sum on the right is added to the equation in the next line.
1+4=5
5+2+5=12
12+3+6=21
Using this method, 21+8+11 would equal 40.
But there’s another way to solve this equation.
For every line, if you multiple the second number by the first number before adding the two, the equations are also consistent.
1+(4x1)=5
2+(5x2)=12
3+(6x3)=21
Using this method, you get a different answer. 8+(8x11) = 96.
But there’s something odd about the equation. The first three equations follow a pattern where the numbers increase by one from the ones below (1+4, 2+5), but 8+11 is a huge jump from 3+6.
If you insert the “missing” equations, you get a different sum using the first method.
1+4=5
5+2+5=12
12+3+6=21
21+4+7=32
32+5+8=45
45+6+9=60
60+7+10=77
77+8+11=96.
It turns out that the two different ways of solving the riddle are the same after all.
