Answer:
The answer is 0.3^2 x 10 = the last number to get 0.9
then 0.9^2 = 0.81 x -10 = 8.1 the actual jump = + 1
We go back 1 places before to do missing sum
so that 0.3 x 1 = 0.3 x -9 = -2.7
Therefore the +1 numbers are decreasing from 10 to -10 then increasing in negative value from -10 to -9 etc.