TMUA 2019 · Paper 2 · Question 4
SaveConsider the following conjecture:
If is a positive integer that consists of the digit followed by an odd number of digits and then a final digit , then is a prime number.
Here are three numbers:
I (which is a prime number)
II (which equals )
III (which equals )
Which of these provide(s) a counterexample to the conjecture?