Text 3221)
The Lord Instructs Sanātana Gosvāmī
181
PURPORT
In one day of Brahmā, there are 14 Manus, and all of them are considered to be  manvantara-avatāras  of the Supreme Personality of Godhead. Thus in one month of Brahmā's life, there are 420  manvantara-avatāras , or Manus. In one year (360 days) of Brahmā's life, there are 5,040 Manu incarnations. Thus for the one hundred years of Brahmā's life, there is a total of 504,000  manvantara-avatāras .
TEXT 3211
চৌদ্ধে এক দিনে, মাসে চারিশত বিশ ।।
ব্রহ্মার   বৎসরে পঞ্চসহস্র চল্লিশ  ॥  ৩২১  ॥  ।
caudda eka dine, māse cāri-śata biśa brahmāra vatsare pañca-sahasra calliśa
SYNONYMS
caudda —14;  eka dine —in one day;  māse —in one month;  cāri-śata biśa —420;  brahmāra vatsare —in one year of Brahmā;  pañca-sahasra calliśa —5,040 avatāras.
TRANSLATION
“There are 14 manvantara-avatāras in one day of Brahmā, 420 in one month, and 5,040 in one year.
TEXT 3222
শতেৈক  বৎসর হয় ‘জীবন’ ব্রহ্মার ।।
পঞ্চলক্ষ চারিসহস্র মন্বন্তরাবতার  ॥ ৩২২ ॥   ॥
śateka vatsara haya ‘jīvana’ brahmāra pañca-lakṣa cāri-sahasra manvantarāvatāra
SYNONYMS
śateka vatsara haya —there are one hundred years;  jīvana —the duration of life;  brahmāra —of Brahmā;  pañca-lakṣa —500,000;  cāri-sahasra —4,000;  manu-antara-avatāra —incarnations of Manu.
TRANSLATION
“During the hundred years of Brahmā’s life, there are 504,000 manvantara-avatarās.