While awaiting the arrival of material from a Tirukkanda Panchanga held by the Adyar Library, all my attempts to arrive at the needed eighteen million years figure have failed, whether using the 1:2:3:4 ratio or the 1:2:3:4:5:6:7 ratio. At the same time, I have found no hint of anything but the traditional figures in any of the pañcāṅga material that I have. The 18,618,725 or 18,618,728 years figure that we seek is beginning to look suspiciously like a mistaken transcription from the Tirukkanda Panchanga, or possibly a misprint in it.

A traditional pañcāṅga may give the length of a manvantara, which as stated earlier is 306,720,000 years (before the addition of the 1,728,000 years sandhi period at the end). It may give the elapsed years of the current or Vaivasvata manvantara, which as stated earlier is 120,532,986 years up to the year 1884 C.E. It may then give the number of years still remaining in the current or Vaivasvata manvantara, which in the year 1884 C.E. would be 186,187,014 years (again not counting the 1,728,000 years sandhi period at the end of the manvantara). If one of the last three digits was mistakenly omitted from this figure when it was transcribed from the Tirukkanda Panchanga (or even if there was a misprint in that issue of the Tirukkanda Panchanga), we would have 18,618,701 or 18,618,704 or 18,618,714, suspiciously like the 18,618,725 or 18,618,728 years figure that we seek.

Background information on what must be the Tirukkanda Panchanga, although it is not called that, may be found in Sankar Balakrishna Dikshit’s book, Bharatiya Jyotish Sastra, vol. 2, pp. 181-182, and 285-286 (available online, http://www.scribd.com/doc/76935732/Bharatiya-Jyotish-Sastra-2). It is there called the Dṛggaṇita Pañcāṅga, by Cintāmaṇi Raghunāthācārya. It began being published in Śaka 1791, or 1869 C.E.