+0  
 
0
1
0
avatar+314 

We call a number cozy if every digit in the number is either a $3$ or next to a $3.$  For example, the numbers $333,$ $83,$ $303,$ and $3773$ are all cozy, but the numbers $32423,$ $786,$ $340,$ and $3999$ are not cozy.

 

How many positive $10$-digit numbers are cozy?

 
 Oct 19, 2024

1 Online Users