Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 9 · Vastu, Griha Pravesha
वास्तु गृहप्रवेशश्च
साध्यवर्गः पुरः स्थाप्य पृष्ठतः साधकं न्यसेत् ।व्यत्यये नाशनं तस्य ऋणमध्यं धनाच्छुभम् ॥ ५६१ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 561.
Put the letter group of the sadhya (the place sought) in front. Put the group of the sadhaka (the person seeking it) behind. Taken the other way round, the figure gives his loss. When the debt is smaller than the gain, it is good.
Simple meaning: Compare the letter groups of the place and the person. It is good when gain is more than debt.
आरभ्य साधकं घिष्ण्यं साध्यं यावच्चतुर्गुणम् ।
Count the stars from the person to the place, multiply by four, divide by seven. The remainder shows gain.
विस्तार आयामगुणो गृहस्य पदमुच्यते ।
Multiply breadth by length to get the area. Six figures are worked out from it.
धनाधिकं गृहं वृद्ध्यै ऋणाधिकमशोभनम् ।
A house with more gain than debt is good. An odd aya point is good; an even one can bring poverty.