Skip to content / Đến nội dung
ThichHocToan.com

MathNet 2019-part-02 — 184 problems (EN–VI) Question 98

Math Olympiad Vault · MathNet 2019-part-02 — 184 problems (EN–VI)

Question 98

A square board whose squares are coloured in either black or white is called *beautiful* if a rotation by $90^\circ$ does not change its appearance.
How many different $5 \times 5$ beautiful boards are there? (Azra Tafro)