3-42EXCLUSIVE NOR (X-NOR) circuits produce a 1 output when all inputs are 0 and when more than1 input is 1.QUARTER ADDERcircuits produce the sum of two numbers but do not generate a carry.HALF ADDERcircuits produce the sum of two numbers and generate a carry.FULL ADDERcircuits add a carry to obtain the correct sum.PARALLEL ADDERcircuits use full adders connected in parallel to accommodate the addition ofmultiple-digit numbers.STANDARD SYMBOLSdepict logic circuitry with blocks, showing only inputs and outputs. Oneblock may contain many types of gates and circuits.SUBTRACTIONin binary is accomplished by complementing and adding.FLIP-FLOPare bistable multivibrators used for storage, timing, arithmetic operations, and transferof information.R-S FFshave the Q output of the FF HIGH in the set mode and LOW in the reset mode.