MathDB

Let

n

be a

d

-digit (i.e., having

d

digits in its decimal representation) positive integer not divisible by

10

. Writing all the digits of

n

in reverse order, we obtain the number

n'

. Determine if it is possible that the decimal representation of the product

n\cdot n'

consists of digits

8

only, if (a)

d = 9998

; (b)

d = 9999?

Problem Statement