The Mathematics of Charity

Money given in charity to a suitable person is guaranteed bank balance in the next life. Such charity is recommended to be given to a brahmana. If the money is given in charity to a non-brahmana (without brahminical qualification) the money is returned in the next life in the same proportion. If it is given in charity to a half-educated brahmana, even then the money is returned double. If the money is given in charity to a learned and fully qualified brahmana, the money is returned a hundred and a thousand times, and if the money is given to a veda-paraga (one who has factually realized the path of the Vedas), it is returned by unlimited multiplication.

– Srila Prabhupada, Srimad Bhagavatam 2.3.17 purport