It is 3000000000.
To round off 128,674 to leave one nonzero digit, you would round it to 100,000.
It is 300000.
It is 6000000.
It is 300.
It is 500.
500
It is 90000.
500500
It is 5000000.
485 6 592 128 674
Because it ends with a five, it rounds up to become 490.