Brihat Parashara Hora Shastra
पूर्ण राश्यादिगे चान्ते हानिर्मध्येऽनुपाततः । योगकारकखेटांशयोगस्तत्संख्यया हृतः ॥ ४५॥
Rectifications. If the contributor is in the beginning of a Rāśi, his donation will be full and it will be nil, if he is at the end of a Rāśi. For intermediary placements rule of three process will apply. Add the longitudes of the contributors and the sum so arrived at must be divided by the number of contributors.
english translation
pUrNa rAzyAdige cAnte hAnirmadhye'nupAtataH । yogakArakakheTAMzayogastatsaMkhyayA hRtaH ॥ 45॥
hk transliteration by Sanscript