+100 Number Series Puzzles Questions with Answers - 1

Ans: 70

The sequence progresses – 18, - 17, -18, -17.

Ans: 15 and 11.

1 + 2 + 3 + 4 = 10, then insert next two numbers 11, 12 and add digits 1 + 1 + 1 + 2 = 5.
Insert next two numbers 6, 7 and add digits 6 + 7 = 13.
Insert next two numbers 14, 15 and add digits 1 + 4 + 1 + 5 = 11.

Ans: 16

Numbers are primes, reversed 31 – 37 - 41 – 43 – 47 – 53 – 59 – 61

Ans: 1881

19 x 99

Ans: 25, 29

There are two alternate sequences:
start at 10 and add 3, 5, 7;
start at 50 and deduct 5, 7, 9.