From logic Blocks.
Left side: Two binary 4 bit numbers (input)
Left column number N1
Right column number N2
LSB = top input each column
N1.0 N2.0 ----
N1.1 N2.1 ---- N3.3 N3.2 N3.1 N3.0
N1.2 N2.2 ---- CarryOverBit
N1.3 N2.3 ----
Right side output LEDs N3 and Red led for final carry bit (output and interface to cascading adders)
