Find number in 2022-th position out of several four-digit numbers
Source: Cyprus 2022 Junior TST-1 Problem 4
February 21, 2022
combinatoricscounting
Problem Statement
Consider the digits .
(a) Determine the number of seven-digit numbers with distinct digits that can be constructed using the digits above.
(b) If we place all of these seven-digit numbers in increasing order, find the seven-digit number which appears in the position.