MathDB

Girls in Math at Yale 2021 Problem 8: ABBA

Source:

February 27, 2021

Yalecollege

Problem Statement

Let

A

and

B

be digits between

0

and

9

, and suppose that the product of the two-digit numbers

\overline{AB}

and

\overline{BA}

is equal to

k

. Given that

k+1

is a multiple of

101

, find

k

.
Proposed by Andrew Wu