I think you are missing the point here. The only even prime is 2. The only prime ending with a 5 is 5.
The last digit of a prime bigger than 5 can only be 1, 3, 7 and 9.
The last digit of a prime bigger than 5 can only be 1, 3, 7 and 9.
also, you're focused on base 10. And that 1,3,7,9 is the basis of the how i remember them: 11,13,17,19 then 23 AND ALSO 101,103,107,109, and then 113. but why!?
I learned that all twin primes in base 4 either end in 1 xor 3. and I know that all primes congruent to 1 modulo 4 can factorized into a complex number with its conjugate (Gaussian primes). But I don't understand this, I only 'know it'
And then, I figured that all the twin primes in base 6 are always end in 5 then in 1. and that's it, this is supposed to be a question by the way
I think I gotta somehow get a better understanding of Mersenne and Eisenstein primes, but I don't like jumping through 'bureaucratic'-academic hoops to get things explained to me. it's only numbers, I have other things to do
I.e
999999999999995%5=0 999999999999992%2=0
Thus they are not prime numbers.
but the numbers are not (only) how they're written down!
meh...
does this answer your question? if not, maybe this can help: https://www.youtube.com/watch?v=BdOtR2A5agc