If number end in 2 or 5, is divisible by 2 or 5. So number ending in 2 or 5 cannot be prime. Math no hard to understand!
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