Integers include 0, the negative numbers without fractional parts, and the positive numbers without fractional parts.

The "without fractional parts" part of the description implies that all of the integers are whole numbers.

Therefore, if you are adding integers, you are adding whole numbers.

The correct spelling is "kisses," as it is the plural form of the verb "kiss." "Kiss's" would be incorrect as it implies possession by adding an apostrophe+s.

The law of diminishing returns implies that adding one factor of production does not always mean an increase in output. In agriculture, adding fertilizer may increase output, but if too much fertilizer is used, it may end up poisoning the plants.

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.

Her reaction implies that she was not happy with the news.