Why negative numbers coming in Fibonacci series after 23 terms?

Answer 1

They don't. If you add two positive numbers, the result will always be a larger positive number. You are probably doing this with a computer program; in this case, you may get a numeric overflow. Precautions should be taken to detect this overflow, and give appropriate error messages. Alternately, you can use a data type that supports larger numbers - for example in Java, use long instead of int, or for even larger numbers, use the BigInteger class, which supports an arbitrary number of digits (at the expense of slower processing).

Answer 2

Negative numbers do not naturally occur in the Fibonacci sequence. The sequence begins with 0 and 1, and each subsequent term is obtained by summing the two preceding terms. If negative numbers seem to be appearing after 23 terms, it is likely due to a mistake or misinterpretation in the calculation or observation.