426
Śrīmad-Bhāgavatam
[Canto 3, Ch. 11]
PURPORT
The duration of life of a Manu comprises seventy-one sets of four millenniums, as described in the  Viṣṇu Purāṇa . The duration of life of one Manu is about 852,000 years in the calculation of the demigods, or, in the calculation of human beings, 306,720,000 years.
TEXT 25
मन्वन्तरेषु मनवस्तद्वंश्या ऋषयः सुराः । म्बन्ति चैव युगपत्सुरेशाश्वानु ये च तान् ॥२५॥
manv-antareṣu manavas tad-vaṁśyā ṛṣayaḥ surāḥ bhavanti caiva yugapat sureśāś cānu ye ca tān
manu-antareṣu —after the dissolution of each and every Manu;  manavaḥ —other Manus;  tat-vaṁśyāḥ —and their descendants;  ṛṣayaḥ —the seven famous sages;  surāḥ —devotees of the Lord;  bhavanti —flourish;  ca eva —also all of them;  yugapat —simultaneously;  sura-īśāḥ —demigods like Indra;  ca —and;  anu —followers;  ye —all;  ca —also;  tān —them.
TRANSLATION
After the dissolution of each and every Manu, the next Manu comes in order, along with his descendants, who rule over the different planets; but the seven famous sages and demigods like Indra and their followers, such as the Gandharvas, all appear simultaneously with Manu.
PURPORT
There are fourteen Manus in one day of Brahmā, and each of them has different descendants.
TEXT 26
एष दैनन्दिनः सर्गो ब्राह्मस्त्रैलोक्यवर्तनः । तिर्यङ्नृपितृदेवानां सम्मवो यत्र कर्ममिः ॥२६॥
eṣa dainandinaḥ sargo brāhmas trailokya-vartanaḥ