The book is now available! 1071
(another Prime Pages' Curiosity)
Prime Curios!
Curios: Curios Search:
 

Participate:
Share
+ The smallest composite number ending in 1, 3, 7 or 9 that yields no primes if its first digit is changed. I.e., 2071, 3071, 4071, 5071, 6071, 7071, 8071 and 9071 are all composite numbers.




Prime Curios! © 2000-2017 (all rights reserved)