My question: what a formula for finding the number of numbers no greater than n that are divisible by all their suffixes.
e.g: 5, 25, 125, 0125, 70125 are divisors of 70125.
$refinement: \overline{0...0a_1a_2...} = \overline{a_1a_2...}$
My question: what a formula for finding the number of numbers no greater than n that are divisible by all their suffixes.
e.g: 5, 25, 125, 0125, 70125 are divisors of 70125.
$refinement: \overline{0...0a_1a_2...} = \overline{a_1a_2...}$