Which operation would be applied to express '800 more than Biloxi's population'?

To express "800 more than Biloxi's population," the appropriate operation is addition. This is because the phrase indicates that you start with the current population of Biloxi and then add 800 to it.

For instance, if Biloxi's population is represented as ( P ), then "800 more than Biloxi's population" would mathematically be expressed as ( P + 800 ). The use of addition captures the idea of increasing the population by a specific amount, in this case, 800.

Other operations like subtraction, multiplication, and division do not fit the context of increasing a quantity by a certain value. Subtraction would imply reducing the population by 800, multiplication would suggest scaling the population by 800, and division would indicate splitting the population into groups, none of which align with the idea of simply adding to the existing population.