Replace each of the letters with a unique digit from 0 to 9 such that you "hop" from one criterion to the next:
11111 AB is Prime,
11111 BCD is a Triangle,
11111 DEF is a Square and
11111 FGH is a Fibonacci number,
111111111111111 and none begin with a zero.
What 8-digit numbers are formed by this process?
What is significant about the highest and lowest?
* This can be logically deduced albeit a little time consuming.