computer science
posted by Drake on .
What is the binary representation of the following hexadecimal number? What are the decimal numbers they represent when interpreted as undesigned integers.
(a) F4
(b) 9F

A hexadecimal digit can take up to 16 values, from 0 to 15. In order to represent values beyond 9 in one single digit, the digits A,B,C,D,E,F are used to represent 10,11,12,13,14,15 respectively.
Since we can also express 0 to 15 in 4 binary digits, there is a frequent need for conversion between hex and binary digits. Here is a conversion table:
hex binary
0 0
1 1
2 10
3 11
4 100
5 101
6 110
7 111
8 1000
9 1001
A 1010
B 1011
C 1100
D 1101
E 1110
F 1111
So E6 can be converted to binary digit by digit by combining E=1110 and 6=0110 into 11100110.
You can read more about the subject here:
http://en.wikipedia.org/wiki/Hexadecimal 
On your PC you have good calculator.
Start¨Programs¨Accessories¨Calculator
When you open Calculator clik on View, then click Scientific.In up left angle you have numbers systems Hex Dec Oct and Bin. Click Hex.Use numbers and letters in down right angle to type some hexadecimal number. Then in up left angle click for some of numbers system and you representation. 
You will see representation of this nuber in some other numbers system.