Answer:
rational numbers
Explanation:
You want to know the subset of numbers containing the number -9.09090909.
Rational numbers
Any finite or repeating decimal is a rational number. It can be expressed as the ratio of two integers.
The given number has exactly 9 digits, so is a finite decimal number. It is a rational number.
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Additional comment
If it were -9.0909... (repeating), it would be equivalent to -100/11, also a rational number.
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