# Negative numbers shown in bits

Dale DeMott

Ranch Hand

Posts: 515

posted 15 years ago

Okay.. so here's an easy one for you. How can I represent -4 in bits. Any good rule of thumb would be great so its easy to remember how to do it later. I understand the positive 4. Thats easy. 0100

Thanks

-Dale

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What's this H2SO4 doing in my fridge?? ( thud )

Thanks

-Dale

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What's this H2SO4 doing in my fridge?? ( thud )

By failing to prepare, you are preparing to fail.<br />Benjamin Franklin (1706 - 1790)

Cindy Glass

"The Hood"

Sheriff

Sheriff

Posts: 8521

Dave Vick

Ranch Hand

Posts: 3244

posted 15 years ago

Dale

To find the negative value of a number you use the twos compliment:

1. take the positive number and flip all the bits (turn 1's into 0's and 0's into 1)

2. add 1 to the result

so for your example of -4

4 is

00000000 00000000 00000000 00000100

flip the bits

1111111 11111111 11111111 11111011

add 1

1111111 11111111 11111111 11111100

this is -4 in binary.

hope that helps

Dave

To find the negative value of a number you use the twos compliment:

1. take the positive number and flip all the bits (turn 1's into 0's and 0's into 1)

2. add 1 to the result

so for your example of -4

4 is

00000000 00000000 00000000 00000100

flip the bits

1111111 11111111 11111111 11111011

add 1

1111111 11111111 11111111 11111100

this is -4 in binary.

hope that helps

Dave

Dave