# Advent calendar 2019

## 4 December

There are 5 ways to tile a 3×2 rectangle with 2×2 squares and 2×1 dominos.

Today's number is the number of ways to tile a 9×2 rectangle with 2×2 squares and 2×1 dominos.

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There are 5 ways to tile a 3×2 rectangle with 2×2 squares and 2×1 dominos.

Today's number is the number of ways to tile a 9×2 rectangle with 2×2 squares and 2×1 dominos.

Not Roman numerals

List of all puzzles