3-9of 0 and a carry (C_{2}) of 1. By reading the outputs (C_{2}, S_{2}, and S_{1}), we see that the sum of 11_{2} and 01_{2} is100_{2}.Figure 3-10. —Parallel addition.As you know, the highest binary number with two digits is 11_{2}. Using the parallel adder, let’s add112and 11_{2}.First, apply the addend and augend to the A and B inputs. Calculate the output of each full adderbeginning with full adder 1. With A_{1} and B_{1} at 1, S_{1} is 0 and C_{1} is 1. Since all three inputs (A_{2}, B_{2}, and C_{1})to full adder 2 are 1, the output will be 1 at S_{2} and 1 at C_{2}. The output of the circuit, as you read left toright, is 110_{2}, the sum of 11_{2} and 11_{2}.Parallel adders may be expanded by combining more full adders to accommodate the number ofdigits in the numbers to be added. There must be one full adder for each digit.Q6. What advantage does a half adder have over a quarter adder?Q7. An X-OR gate may be used as what type of adder?Q8. What will be the output of a half adder when both inputs are 1s?Q9. What type of adder is used to handle a carry from a previous circuit?Q10.How many full adders are required to add four-digit numbers?Q11.With the inputs shown below, what will be the output of S_{1}, S_{2}, and C_{2}?

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