Topic 5 - Signed binary using two's complement

Question 1

What is signed binary?

Answer 1

Signed binary numbers are encoded to include a positive or negative sign

Question 2

Signed numbers are represented in computers using what method?

Answer 2

Signed numbers are represented in computers using the two’s complement method

Question 3

How does two’s complement work?

Answer 3

The most significant bit will indicate 1 for a negative number and 0 for a positive number.

Question 4

How can you do two’s complement subtraction?

Answer 4

Add a negative number.

Question 5

Covert 15 to -15 in binary

Answer 5

0000 1111 = 15
1111 0000    (flip the bits)
1111 0001     (Add 1)

Question 6

Subtraction using two’s complement

15 - 12

Answer 6

15 = 0000 1111
12 = 0000 1100 which is 1111 0100 in two's complement

0 0 0 0 1 1 1 1
1 1 1 1 0100
——————–
0000000011 or 3

15 - 12 = 3