'Seventy seven' in the Bible

All the days of Lamech were seven hundred and seventy-seven years, and he died.

He captured a young man {from Succoth} and questioned him. [The young man] listed for him the commanders of Succoth and its elders, seventy-seven men.

The exiles that returned from captivity offered burnt offerings to the God of Israel; twelve bulls for all Israel, ninety-six rams, seventy-seven lambs, and twelve goats as a sin offering. All was a burnt offering to Yahweh.