[futurebasic] Re: Binary help (somewhat OT)

Message: < previous - next > : Reply : Subscribe : Cleanse
Home   : November 1997 : Group Archive : Group : All Groups

From: Chris <behmc@...>
Date: Tue, 18 Nov 1997 19:06:19 -0500
>On 11/18/97 9:11 AM, Chris <behmc@...> said:
>>Can someone give me the basics of binary addition and subtraction?  I think
>>I understand (and can do) binary addition, but subtraction is giving me
>It is just like subtraction in decimal.
> 26
>  9
>Each digit has a "weight." In decimal it is powers of ten:
>   1000s          100s           10s                1s
>or 10 to the 3rd, 10 to the 2nd, 10 to the 1st, and 10 to the zero.
>It goes on in each direction ad infinitum.
>The same is true for all numbering systems, binary, octal, hexadecimal,
>base-12 and so on.
>  11010
> -10001
>   1001
>   32s           16s           8s            4s            2s
>  1s
>or 2 to the 5th, 2 to the 4th, 2 to the 3rd, 2 to the 2nd, 2 to the 1st,
>and 2 to the zero.
>So in the example above we have a "2 to the zero" subtracted from a null,
>so we have to borrow a
>"2 to the 1st," or a value of two from the next digit, subtract the "2 to
>the 1st" (a one), leaving us with a value of 1 for the 2 to the zero
>We borrowed that 2 to the 1st digit so it is now zero.
>We move to the left and find a zero in the 2 to the 2nd columns.
>In the two to the 3rd column we subtract 0 from 1 leaving a one in that
>column in the result.
>Move on to the 2 to the 4th column, subtract 1 from one, result is zero,
>and we're done.
>The same principles apply to all numbering systems.
>Caryn Roberts

THANK YOU!  That's exactly what I was looking for.  What eluded me was the
idea that each place was "greater" then 1 (unless it was the first colum).
A holdover from years of decimal math caused it.  Now it makes _much_ more

Again, thanks,