Number Series Puzzles Questions

23. What number should replace the question mark?
  What is the next number?
Answer
Ans = 0.
Looking down and across the sum of alternate numbers are equal, for example
7 + 9 = 10 + 6
5 + 3 = 1 + 7
24. What number should replace the question mark?
  What is the next number?
Answer
Ans = 46.
Start at 1 and work clockwise adding 3, 6, 9, 12, 15, 18.
123456789101112131415




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