Sadam means 100. In such a case, why we do sadabishekam at age of 80?

Sadabhishekam

   Sadabhishekam :- 1000 Full Moon Life Those Who Have Witnessed 1000 Full Moon Days Will Be Considered As Sadabhisheki. After Completing 80 Years And Starting 81 Will Be Treated Sadabhisheka Period. In Their 81 Years Life Time Full Moon ( Pournami) Day Will Be Visible For 1000 Times. Those Who Are Living For 1000 Pournami Days He Will Definitely Attain The Moksha By The Blessings Of Lord Chandra. Some Of Them Use To Perfom Mritunjya Homa, , Ekadasa Rudra, Udakasanthi Etc., Any One Taking Blessing From This Sadabisheki, His Life Will Become Worthy.

shashtiaptha poorthi represents the completion of 60 years of age, bheemaratha shanthi completes 70 years of age, and sadabhishekam completes 80 years of age.