Brihat Parashara Hora Shastra
पदस्य भुक्तघट्याद्यैः स्वाब्दमानं हतं ततः । भभोगांघ्रिहृतं भुक्तं भोग्यं मानाद् विशोधितम् ॥ ९२॥
Multiply the past Ghatikas, Palas etc. of the present Pad of the Nakshatr by the number of years and divide the product by the fourth part of Bhabhog. The years etc. so obtained may then be deducted from the total Dasha period. The result will be the balance of Dasha at birth in years, months etc.
english translation
padasya bhuktaghaTyAdyaiH svAbdamAnaM hataM tataH । bhabhogAMghrihRtaM bhuktaM bhogyaM mAnAd vizodhitam ॥ 92॥
hk transliteration by Sanscript