HKIMO 2018 Grade 5 National Final (Heat) Set 03 Question 17

A square is formed by 128 rectangles, each measuring 2 cm by 1 cm. Find the decrease in perimeter in cm after they are combined.

Source glossary (English–Vietnamese): Square: hình vuông; Rectangles: hình chữ nhật; Decrease: giảm đi; Perimeter: chu vi.