"Sketch a combinational circuit which takes as input, two 4-bit binary numbers, A3A2A1A0 and B3B2B1B0, and which outputs the 8-bit product P7P6P5P4P3P2P1P0. Assume that you have available sixteen 2-input AND gates and three 4-bit adders. Please explain the reasoning behind your design."
After a bit of fiddling I got close to the final circuit but I found that three 4-bit adders wouldn't be enough. To save time (and my complete lack of being able to explain anything) I found this, which is almost exactly what I need except it used two 4-bit adders and one 6-bit adder. I want to know if it's even possible to construct a circuit that can multiply two 4-bit numbers using the gates specified above, and if so, how can you do it?
Thanks in advance.