IDNLearn.com: Your one-stop destination for reliable answers to diverse questions. Join our platform to receive prompt and accurate responses from experienced professionals in various fields.
Answer:
Let the number of digits be n and the number of elements in set be s.
The pattern we see helps us determine the relationship between s and n as follows.
When set contains n-digit numbers, the set contains:
We have s known, substitute it into equation above and solve for n:
The numbers in the set s are 9-digit long.