#### Pastafarian

##### New Member

- Joined
- Jul 2, 2007

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- HSC
- 2007

Taken from Heinemann HSC

10.3

4) Perform these subtractions using the twos complement method. Show all working. Write answers in twos complement and sign plus modulus form.

d.) 0000 0110 - 1000 1110

my answer: ones complement 0111 0001

twos complement 0111 0010

difference 0111 1000

This cannot be right as the expected answer should be negative so i took the ones and twos complement of the difference:

ones : 1000 0111

twos : 1000 1000

modulus = 1000 1000, which is -8..........answer asking for 6-142 = -136

The solutions found here: http://www.hi.com.au/softwaredesign/ state

The second number 1000 1110

One’s complement 0111 0001

Add one 0000 0001

Two’s complement 0111 0010

Add first number 0000 0110

Difference 0111 1000

Answer is positive (as expected) so 0111 1000 is also sign plus modulus form.

Help please.

Thanks.

EDIT: gah, 16 views but no-one has come across this problem before??!!

10.3

4) Perform these subtractions using the twos complement method. Show all working. Write answers in twos complement and sign plus modulus form.

d.) 0000 0110 - 1000 1110

my answer: ones complement 0111 0001

twos complement 0111 0010

difference 0111 1000

This cannot be right as the expected answer should be negative so i took the ones and twos complement of the difference:

ones : 1000 0111

twos : 1000 1000

modulus = 1000 1000, which is -8..........answer asking for 6-142 = -136

The solutions found here: http://www.hi.com.au/softwaredesign/ state

The second number 1000 1110

One’s complement 0111 0001

Add one 0000 0001

Two’s complement 0111 0010

Add first number 0000 0110

Difference 0111 1000

Answer is positive (as expected) so 0111 1000 is also sign plus modulus form.

Help please.

Thanks.

EDIT: gah, 16 views but no-one has come across this problem before??!!

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