12 can be made into a prime by changing the 2 to 3; likewise, 63 can be changed into a prime by changing the 6 to 7.

What is the smallest number that cannot changed into a prime by changing a single digit?

Are there infinitely many such numbers?

umm... i dunno why noone thought of this but...

there are an infinite amount of prime numbers

therefore there are an infinite amount of numbers which can have one digit change and be a prime number

unless your asking if there are an infinite amount of numbers that cant be changed into a prime by changing one digit

then, yeah still

the only numbers that can 'change' into a prime are ones with all the same digits minus one
crossing out all these numbers, however still leaves some behind (like 200), especially when primes get really large
as the primes get larger, they are more scarce and fewer of these 'changeable primes' occur
so, yes

Posted by Geoff on 2004-05-06 06:14:29