We know that,
Volume of cuboid = Length × Breadth × Height
Therefore,
Volume of a soap cake = 7 × 5 × 2.5
= 87.5 cm3
Also,
Volume of the box = 56 × 40 × 25
= 56000 cm3
Therefore,
Number of soap cakes = \(\frac{56000}{87.5}\)
= 640 units
Hence,
640 cakes of soap can be placed in a box of the given size