A kind of rectangular floor tile is 30 cm long and 15 cm wide. At least how many such tiles can be paved into a solid square?

A kind of rectangular floor tile is 30 cm long and 15 cm wide. At least how many such tiles can be paved into a solid square?

30 × 15 = 450 30 × 30 = 900 △ 450 = 2 pieces
A: at least 2 floor tiles of 30cm in length and 15cm in width are required