A truncatable prime is a prime number that when you successively remove digits from one end of the prime, you are left with a new prime number.


;Examples:
The number '''997''' is called a ''left-truncatable prime'' as the numbers '''997''', '''97''', and '''7''' are all prime.

The number '''7393''' is a ''right-truncatable prime'' as the numbers '''7393''', '''739''', '''73''', and '''7''' formed by removing digits from its right are also prime.

No zeroes are allowed in truncatable primes.


;Task:
The task is to find the largest left-truncatable and right-truncatable primes less than one million (base 10 is implied).


;Related tasks:
* [[Find largest left truncatable prime in a given base]]
* [[Sieve of Eratosthenes]]


;See also:
* [http://mathworld.wolfram.com/TruncatablePrime.html Truncatable Prime] from MathWorld.]
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