MathDB
Ecuadorian 5-digit numbers - 2016 Ecuador Juniors (OMEC) L2 p1

Source:

October 24, 2022
number theoryDigits

Problem Statement

A natural number of five digits is called Ecuadorian if it satisfies the following conditions: ∙\bullet All its digits are different. ∙\bullet The digit on the far left is equal to the sum of the other four digits. Example: 9135091350 is an Ecuadorian number since 9=1+3+5+09 = 1 + 3 + 5 + 0, but 5421054210 is not since 5≠4+2+1+05 \ne 4 + 2 + 1 + 0. Find how many Ecuadorian numbers exist.
Back to ProblemsView on AoPS