MathDB

Let

\overline{abcd}

4

digit number, such that we can do transformations on it. If some two neighboring digits are different than

0

, then we can decrease both digits by

1

(we can transform

9870

8770

9760

). If some two neighboring digits are different than

9

, then we can increase both digits by

1

(we can transform

9870

9980

9881

). Can we transform number

1220

to:

a)

2012

b)

2021

Problem Statement