What the next number should be 8 6 9 5 10 4 11?

Answer 1

It is possible to find a polynomial of order 7 which will predict any number of your choice as the next number.

The following polynomial of order 6:

U6 = (6n6 - 142n5 + 1325n4 - 6180n3 + 15004n2 - 17663n + 7890)/30 will fit the above points and, for n = 8, predicts the next number as 323.

Alternatively, you have two inter-spliced series: odd terms increasing by one, even terms decreasing by one. Accordingly, the next term is 3.

Answer 2

2