In Jainism, the concept of "Aara" (also spelled "Ara" or "Ārā") refers to the divisions of time cycles in the universe. Each time cycle (Kalachakra) is divided into six periods called "Aara."

The number "90" is significant in relation to the third Aara (Suṣama-duṣamā) of the current descending half-cycle (Avasarpini). According to Jain scriptures, the third Aara lasts for 90,000 years.

To summarize:

• Third Aara (Suṣama-duṣamā): Duration is 90,000 years.
• So, the number 90 (specifically, 90,000) is associated with the third Aara in Jain time cycles.

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