[VA] Short & Sweet Math Challenge #25 "San Valentin's Special: Weird Math"

[Valentin Albillo]

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Thanks for your interest and for participating, some quick answers to your questions:

Vincent Weber Wrote:Is the Python syntax available on the HP Prime CAS allowed ? Smile [...] If you ban Python altogether, I shall try with RPN on Free42 Smile

If it's available for the HP Prime then it's technically allowed but I'd rather have a program in Hppl for the Prime or in RPN/RPL/BASIC/FORTH/Assembler/etc. for any other HP calc. Anyway, your choice.

robve Wrote:But some information is missing about the PP definition: do you mean that changing any digit to any other digit ALWAYS produces a composite number? So for example 17 is not a PP because 7->9 gives 19?

Yep. If changing any single digit to any other digit results in a prime number, the original one is not a PP.

Regards.
V.