2-digit numbers that are assigned 8
Source: XV May Olympiad (Olimpiada de Mayo) 2009 L1 P1
September 22, 2022
Digitsnumber theory
Problem Statement
Each two-digit natural number is assigned a digit as follows: Its digits are multiplied. If the result is a digit, this is the assigned digit. If the result is a two-digit number, these two figures are multiplied, and if the result is a digit, this is the assigned digit. Otherwise, the operation is repeated. For example, the digit assigned to is since ; the digit assigned to is since , , . Find all the two-digit numbers that are assigned .