Manasara 30.88

30.88

etattadeva saṃyuktaṃ harmyāṇāṃ mānakalpanam
ṣaṭsaptāṣṭakavṛddhiḥ syāddvādaśāntaṃ kṣayaṃ nayet

Joined with this and that is the determination of the measurement for the edifices: / Let there be an increase by six, seven, or eight, and one should deduct [by twelve] up to twelve;