-5
The next number is -21
109 Answered by G.S.Nair
17
26
The series seems to be "add 3," so the next number in the series would be 12 followed by 15.
15
11
15
The pattern is add three and then multiply by three. The next number is 174.
20
The next time the series is playing is December 15.
-5
The next number is -21
53
109 Answered by G.S.Nair
The series 1 6 10 13 15 (1+5=6; 6+4=10, 10+3=13; 13+2=15) is completed by 15+1=16. The answer is 16.