It is 710, as in the question. There is no need to add a decimal point. Adding a decimal point and one or more 0s is wrong because that implies a degree of precision that cannot be justified.
You have already expressed it as a decimal.
Yes, it can.
710
1.9 IS in decimal form.
8.5 IS in decimal form.
710
710
710 as a decimal is the same as 710.0
710
You have already expressed it as a decimal.
To change 710 to a decimal, divide it by 100. The result is 7.1. Rounding it to the nearest hundredth means keeping two decimal places, so the rounded decimal form of 710 is 7.10.
7/10 = 0.7
7/10 = 0.7
7.10 = 710%
7.10 = 710%
1710.0
If you mean 2 and 7/10 then as a decimal it is 2.7