Is the Addition of These Three Binary Numbers Correct?

[kidi3]

Homework Statement

Addition.

3 binarynumbers

101111000
10111110
+ 10001101

The Attempt at a Solution

111
111111
101111000
10111110
+ 10001101
1011000011

Is it correct?

 

[jedishrfu]

You need to align them to make it easier to evaluate. Also I think your carries weren't lined up either.

   101111000
    10111110
 +  10001101
---------------
  1011000011

Yes, I get the same answer.

Of course you can check your result by converting back to decimal

376 + 190 + 141 = 707

 

[kidi3]

Well.. that's what i hoped wasn't the case...

My books says that it's incorrect.

It says that the answer should be

http://snag.gy/mjQzv.jpg

 

[Dick]

Well.. that's what i hoped wasn't the case...

My books says that it's incorrect.

It says that the answer should be

http://snag.gy/mjQzv.jpg

The books answer appears to only be adding the two numbers in the lines labelled X and Y and getting the sum in the line labelled X+Y. It's not adding three numbers.

 

[phinds]

Well.. that's what i hoped wasn't the case...

My books says that it's incorrect.

It says that the answer should be

http://snag.gy/mjQzv.jpg

Note that the image you posted SPECIFICALLY only adds X and Y. It does not include the top number of the three.

 

[kidi3]

Yeah.. i just realized it myself..
well it only took me 3 hours to realize it..

but thanks anyway :)

 

[jedishrfu]

The very first line is labeled with C to indicate the carries from column to column.

 

[phinds]

The very first line is labeled with C to indicate the carries from column to column.

HA ! good catch !