-13
It is 15-4 = 11
the next number is 5 and the one after that is 15
What would be the next number in this series 15 12 13 10 11 8?
the answer is 1
14
17
11 15 16
it is the number such that 15 added to negative 15=0
4 + (-15) = 4 - 15 = -11
8
10 4 3 11 15 9 8 16 20....
No negative number is equal to 15. Also, the only positive number equal to 15 is . . . . . 15.