What is the greatest prime you must consider to test whether 7280 is prime?

Answer 1

In principle, the largest prime that is less than or equal to the rounded down value of square root of 7280.

Since sqrt(7280) = 85.32, then 85 is the largest factor that 7280 can have.

You can therefore stop at the largest prime before that, which is 83.

In this particular example, though, you can stop after 2, because you find that 7280 is composite.

In principle, the largest prime that is less than or equal to the rounded down value of square root of 7280.

Since sqrt(7280) = 85.32, then 85 is the largest factor that 7280 can have.

You can therefore stop at the largest prime before that, which is 83.

In this particular example, though, you can stop after 2, because you find that 7280 is composite.

In principle, the largest prime that is less than or equal to the rounded down value of square root of 7280.

Since sqrt(7280) = 85.32, then 85 is the largest factor that 7280 can have.

You can therefore stop at the largest prime before that, which is 83.

In this particular example, though, you can stop after 2, because you find that 7280 is composite.

In principle, the largest prime that is less than or equal to the rounded down value of square root of 7280.

Since sqrt(7280) = 85.32, then 85 is the largest factor that 7280 can have.

You can therefore stop at the largest prime before that, which is 83.

In this particular example, though, you can stop after 2, because you find that 7280 is composite.

Answer 2

In principle, the largest prime that is less than or equal to the rounded down value of square root of 7280.

Since sqrt(7280) = 85.32, then 85 is the largest factor that 7280 can have.

You can therefore stop at the largest prime before that, which is 83.

In this particular example, though, you can stop after 2, because you find that 7280 is composite.