please solve by full and half adders

) (a) Figures 1 shows a 4-bit unsigned multiplication. Design a 4-bit variable- constant unsigned multiplier where the constant input b = 13. Show all your design steps and draw the logic diagram using the minimum number of components. 2 , by b2b, bo agbo azbo abo a bo agbab abi ab1 a3b2ab2 a1b2 aoba a3b3a2b3 ab3 aobs P7 P6 PS P4 P3 P2 PIPO Fig. 1 (7marks) Redesign the circuit in (a) using a ROM. Show all your design steps. (4 marks) (b)