A number theory problem by A Former Brilliant Member

Number Theory Level 1

Find the total number of prime numbers in the interval 1 and 500000 whose last digit is 5.


The answer is 1.

A Former Brilliant Member by A Former Brilliant Member

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1 solution

there is only 1 prime number that ends in 5, and that is 5 alone.

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For completeness, we should add the simple reason for this: all integers ending in 5 are divisible by 5. And there is only one prime number, which has 5 as a factor: 5 itself.

Zee Ell - 4 years, 7 months ago

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