Why is there a number n? To judge whether it is prime, we only need to check whether n can be divided by the number between 2 and the root n

Because n = radical n * radical n
If n contains a divisor a greater than the root N and less than N, then n must contain a divisor b greater than 1 and less than the root n
Let n = a * B
Therefore, if a number n has no divisor from 2 to the root n, then there must be no divisor from the root n to n-1, that is, n is a prime number

RELATED INFORMATIONS

1. Let F 1 and F 2 be the left and right focal points of hyperbola x ^ 2 / 4-y ^ 2 = I respectively, and point P satisfy ∠ f 1pf 2 = 90 ° on the hyperbola, then the area of △ f 1pf 2 is
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3. If a and B are not divisible by Prime n + 1, can a ^ N-B ^ n be divisible by N + 1? Can give a proof; can't give a reason,
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8. Use the number 123456 to form the number of four digits without repetition and the odd number is not adjacent
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