The number of full adders and half adders required to add two 16-bit numbers is:
1999
The number of full adders and half adders required to add two 16-bit numbers is:
- A.
8 half-adders, 8 full-adders
- B.
1 half-adder, 15 full-adders
- C.
16 half-adders, 0 full-adders
- D.
4 half-adders, 12 full-adders
Attempted by 65 students.
Show answer & explanation
Correct answer: B
The correct answer is: 1 half-adder and 15 full-adders.
To add two 16-bit numbers with a ripple-carry adder, the least significant bit position has only two inputs: the two least significant bits of the two numbers. Since there is no incoming carry for the first bit, this position needs one half-adder.
Each of the remaining 15 bit positions must add three inputs: one bit from each number and the carry from the previous position. Therefore each of these positions needs a full-adder.
Hence the required hardware is 1 half-adder and 15 full-adders.