Question 1198268
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ALL problems like this can't be answered definitively.  In any given sequence of numbers like these, ANY number next will make a valid sequence -- so it is impossible to know the "right" answer to any such problem.<br>
Your second example shows a simple pattern which MIGHT lead to a correct answer -- although there would be no way to know if it was right.<br>
The other two examples show no obvious pattern, so "solving" them is no more than a guessing game.<br>
Spend as much (or as little!) time as you want looking for possible answers....<br>