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Date: 12/08/98 at 11:15:11
From: Ian hamilton
Subject: number base conversions

I am a mature student on a computing HND. We have just gone through
the followung question in class, but I am still clueless. Convert
110000001101 from base two to hexadecimal.

```

```
Date: 12/08/98 at 12:48:27
From: Doctor Rick
Subject: Re: number base conversions

Hi, Ian. A big part of the reason that we use hexadecimal is that it is
numbers are closely related to binary, but they are shorter and easier

Group the binary digits into groups of 4 starting from the right:

1100 0000 1101

Each group will correspond to one hexadecimal digit. The leftmost digit
in a group is the 8's place; next come the 4's, 2', and 1's places. In
each group, take the numbers for the places that have 1's in them, and

8421 8421 8421
1100 0000 1101
\__/ \__/ \__/
8+4    0  8+4+1
12    0   13

I did the additions in base 10, so now we need to convert base 10 to
base 16. Remember that in hexadecimal:

A = 10; B = 11; C = 12; D = 13; E = 14; F = 15

Why does this work? Each place in a hexadecimal number represents a
power of 16. Thus, the hexadecimal number C0D is 12*16^2 + 0*16 + 13.
Each place in a binary number represents a power of 2. Since 16 = 2^4,
you can write, for instance:

11    3    8    3     2
2   = 2  * 2  = 2  * 16

Therefore, 4 consecutive binary digits can be grouped and a power of
16 extracted from each:

11     10     9     8        3      2      1      0      2
a*2  + b*2  + c*2  +d*2   = (a*2  + b*2  + c*2  + d*2 ) * 16

Since a 4-digit binary number is at most 15 (decimal), each group
converts into one hex digit.

For another source on this topic, please see:

Binary Conversion
http://mathforum.org/dr.math/problems/stirling1.7.98.html

- Doctor Rick, The Math Forum
http://mathforum.org/dr.math/
```
Associated Topics:
High School Number Theory

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