# Binary addition

1. Jan 30, 2013

### kidi3

1. The problem statement, all variables and given/known data
Addition.

3 binarynumbers

101111000
10111110
+ 10001101

3. The attempt at a solution
111
111111
101111000
10111110
+ 10001101
1011000011

Is it correct?

2. Jan 30, 2013

### Staff: Mentor

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

Code (Text):

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

Last edited: Jan 30, 2013
3. Jan 30, 2013

### kidi3

Well.. thats 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

4. Jan 30, 2013

### Dick

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.

5. Jan 30, 2013

### phinds

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

6. Jan 30, 2013

### kidi3

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

but thanks anyway :)

7. Jan 30, 2013

### Staff: Mentor

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

8. Jan 30, 2013

### phinds

HA ! good catch !

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