CC Madhya 20.323

ananta brahmāṇḍe aiche karaha gaṇana
mahā-viṣṇu eka-śvāse brahmāra jīvana
Word for word: 
ananta brahmāṇḍe — in innumerable universes; aiche — in that way; karaha gaṇana — just try to count; mahā-viṣṇu — Lord Mahā-Viṣṇu; eka-śvāse — by one exhalation; brahmāra jīvana — the duration of life of one Brahmā.
Translation: 
“The number of manvantara-avatāras for only one universe has been given. One can only imagine how many manvantara-avatāras exist in the innumerable universes. And all these universes and Brahmās exist only during one exhalation of Mahā-Viṣṇu.