3000
This cannot be properly answered because you did not say what place to round it to. For example; nearest whole number, hundreds, tenths, etc.However, rounded to the nearest whole number, it would become 2 ounces.
1500
It is 346,000 rounded to the nearest 1,000
5500
1100
1000
3000
7.60
It is 600000, as in the question!
0.4
500