First, we need to change all mixed number to improper fraction.
3 1/4=13/4
Volume of box=
13/4×3×1=39/4
Volume of one foam block:
1/4×1/4×1/4=1/64. To find the final answer take:
39/4÷1/64
=39/4×64
=624 blocks. As a result, there are total 624 blocks that can fit into the box. Hope it help!