This problem calls for experimentation.
There are six possible ways to fill the ice box.
Align 7 and 16, 12 and 45, 8 and 48 So 2 * 3 * 6 = 36.
Align 7 and 16, 12 and 48, 8 and 45 So 2 * 4 * 5 = 40.
Align 12 and 16, 7 and 48, 8 and 48 So 1 * 6 * 6 = 36.
There are three left for you to try.