View tc74hc283p datasheet:

TC74HC283P IL00D C-MOS 4-BIT BINARY FULL ADDER —TOP VIEW— 5 A0 3 ?1 OUT 1 VDD 16 A1 14 A2 B2 IN 12 4 B1 IN 2 15 A3 ?0 1 ?1 A2 IN 6 13 A1 IN 3 14 B0 ?2 2 10 B1 ?3 ?2 OUT 15 ?0 OUT 4 13 B2 11 B3 A3 IN A0 IN 5 12 7 9 CI CO B3 IN B0 IN 6 11 ?3 OUT CI 7 10 24 23 22 21 20 DIGIT (CARRY IN) CI CARRY IN CO 8 GND 9 A3 A2 A1 A0 DATA A IN (CARRY OUT ) + B3 B2 B1 B0 DATA B IN CO ?3 ?2 ?1 ?0 CARRY&SUM OUT EX. 1 CI 1 0 1 1 A + 1 0 1 0 B 1 0 1 1 0 OUTPUTS CO ?3 ?2 ?1 ?0