Brihat Parashara Hora Shastra
चन्द्राङ्कांशकला भुक्ताः स्वाब्दमानहता हृताः । द्विशत्या भुक्तवर्षाद्यं ज्ञेयं भोग्यं ततो बुधैः ॥ ९३॥
The past Kalas (minutes) of the Navāńś, in which Candr may be placed, should be multiplied by the years, allotted to the Dasha and the product should be divided by 200. The resulting years etc. will be the expired portion of the Dasha. By deducting them from the total number of years the balance of the Dasha at birth is obtained.
english translation
candrAGkAMzakalA bhuktAH svAbdamAnahatA hRtAH । dvizatyA bhuktavarSAdyaM jJeyaM bhogyaM tato budhaiH ॥ 93॥
hk transliteration by Sanscript