Which number should come after this series? 25 - 24 - 22 - 19 - 15 - ?

Question

10

Answer 1

The next number should be 10. Be cause if we take the difference of each number, it is decreasing negatively

                    24-25 = -1, 

                    22-24 = -2

                    19-22 = -3

                    15-19 = -4 

                    so the next series must have a difference of -5.  and that is 10-15 = -5.