MathDB

We say that a positive integer is guarani if the sum of the number with its reverse is a number that only has odd digits. For example,

249

and

30

are guarani, since

249 + 942 = 1191

and

30 + 03 = 33

. a) How many

2021

-digit numbers are guarani? b) How many

2023

-digit numbers are guarani?

1