OMK 2018 Muda, Section B Problem 2
Source: OMK 2018 Muda, Section B Problem 2
June 21, 2021
number theoryDigits
Problem Statement
Let and be positive integers such that
(i) both and have at least two digits;
(ii) is divisible by ;
(iii) can be changed into by changing its last digit.
Prove that the hundreds digit of the product is even.