It is 5000000.
Oh, dude, the leftmost nonzero digit is basically the first digit in a number that isn't zero. Like, it's the number that kicks off the party and gets things going. So, if you see a number like 503, the leftmost nonzero digit would be 5. Hope that clears things up for ya!
.08 or 8 centavos. If the cut off digit is 5-9 round up. If the cut off digit is 0-4 round down.
10
By adding simple logic you can round off to single digit. In any value you add 0.05 and pick only one digit after the decimal and the result will be the value after rounding off in one decimal place.
To round off 128,674 to leave one nonzero digit, you would round it to 100,000.
It is 400.
It is 300000.
It is 6000000.
It is 300.
It is 500.
It is 3000000000.
500
It is 90000.
500500
It is 5000000.
It is 3000000000.