248=8×3 1

88=8× 1 1

therefore

The greatest common factor of 248 and 88 is 8.

Therefore, the side length of the floor tile is 8 decimeters.

(248÷8)×(88÷8)

=3 1× 1 1

=34 1 (block)

Answer: You need to buy at least 34 1 tile of this kind.