Please help me on these questions, I don't know how to get to these answers. Thank you.

Question 3 : When A and B are two unsigned 4 bit integers, what is the maximum number of bits in the binary value of X = AxB? (Ans : 8)

Question 4 : When A and B are two unsigned 4 bit integers, what is the maximum value of X = AxB? (Ans : 11100001)

Adder 1				Adder 2
Input:	Connect to : (0, 1, or Di where i=0..15)	Input:	Connect to : (0, 1, or Di where i=0..15)	Input:	Connect to : (0, 1, or Di where i=0..15)	Input:	Connect to : (0, 1, or Di where i=0..15)
P0	0	Q0	D8	R0	0	S0	D0
P1	D12	Q1	D9	R1	D4	S1	D1
P2	D13	Q2	D10	R2	D5	S2	D2
P3	D14	Q3	D11	R3	D6	S3	D3
P4	D15	Q4	0	R4	D7	S4	0

In this set of questions, we build a multiplier for two 4-bit unsigned integers A=(A3,A2,A1,A0) and B=(B3,B2,B1,B0). Table 1 shows the arithmetic of this multiplication. Figure 1 shows an incomplete circuit that implements this multiplication. (For simplicity, only the relevant logical components are shown.)

Table 1

					A3	A2	A1	A0	(Value of A)
					B3	B2	B1	B0	(Value of B)
					A3*B0	A2*B0	A1*B0	A0*B0	(Intermediate 1)
				A3*B1	A2*B1	A1*B1	A0*B1		(Intermediate 2)
			A3*B2	A2*B2	A1*B2	A0*B2			(Intermediate 3)
+		A3*B3	A2*B3	A1*B3	A0*B3				(Intermediate 4)
=	X7	X6	X5	X4	X3	X2	X1	X0	(Final result)

Variable:	Expression:	Variable:	Expression:	Variable:	Expression:	Variable:	Expression:
D0 =	A0*B0	D1 =	[D1]	D2 =	[D2]	D3 =	[D3]
D4 =	[D4]	D5 =	[D5]	D6 =	[D6]	D7 =	[D7]
D8 =	[D8]	D9 =	[D9]	D10 =	[D10]	D11 =	[D11]
D12 =	[D12]	D13 =	[D13]	D14 =	[D14]	D15 =	[D15]

A2 A1 Ao B3 B2 , 0 11 10 98 D, D6 D5 D4 D3 D2 D Do 5-bit adder 1 5-bit adder 2 8-bit adder 3