Brihat Parashara Hora Shastra
एवं दीर्घसमाल्पेषु खाब्धयो रसवह्नयः । खण्डा दन्तमितास्तेभ्यः स्फुटमायुः प्रसाधयेत् ॥ ४४॥
In this manner, for long, medium, and short spans, the segments are forty, thirty-six, and thirty-two; from these, one should accurately determine the life expectancy.
english translation
evaM dIrghasamAlpeSu khAbdhayo rasavahnayaH । khaNDA dantamitAstebhyaH sphuTamAyuH prasAdhayet ॥ 44॥
hk transliteration by Sanscript