3 x 1.25 = 3.75
3.75 x 2 = 7.50
The volume of the big box is 7.5cubic feet
A smaller box is 1/4 foot by 1/4 foot by 1/4 foot.
1/4 * 1/4 = 1/16.
1/16 * 1/4 = 1/64
64 small boxes can fit in a cubic foot.
7.5 * 64 = 480
480 small boxes can fit in the bigger box.