Computer Science AS CIE
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data-representation as5 主题
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multimedia as3 主题
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compression as2 主题
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networks-and-the-internet as11 主题
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computers-and-components as5 主题
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logic-gates-and-logic-circuits as2 主题
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central-processing-unit-cpu-architecture as6 主题
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assembly-language- as4 主题
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bit-manipulation as1 主题
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operating-systems as3 主题
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language-translators as2 主题
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data-security as3 主题
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data-integrity as1 主题
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ethics-and-ownership as3 主题
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database-concepts as3 主题
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database-management-systems-dbms- as1 主题
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data-definition-language-ddl-and-data-manipulation-language-dml as1 主题
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computational-thinking-skills as1 主题
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algorithms as4 主题
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data-types-and-records as2 主题
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arrays as2 主题
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files as1 主题
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introduction-to-abstract-data-types-adt as1 主题
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programming-basics as1 主题
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structured-programming as1 主题
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number-systems- as
Exam code:9618
Number bases
What is a number base?
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A number base is the number of different digits or symbols a number system uses to represent values
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Each place in a number represents a power of the base, starting from the right
Denary
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Denary is a number system that is made up of 10 digits (0-9)
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Denary is referred to as a base-10 number system
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Each digit has a weight factor of 10 raised to a power, the rightmost digit is 1s (100), the next digit to the left 10s (101) and so on
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Humans use the denary system for counting, measuring and performing maths calculations
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Using combinations of the 10 digits we can represent any number

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In this example, (3 x 1000) + (2 x 100) + (6 x 10) + (8 x 1) = 3268
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To represent a bigger number we add more digits
Binary
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Binary is a number system that is made up of two digits (1 and 0)
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Binary is referred to as a base-2 number system
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Each digit has a weight factor of 2 raised to a power, the rightmost digit is 1s (20), the next digit to the left 2s (21) and so on
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Each time a new digit is added, the column value is multiplied by 2
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Using combinations of the 2 digits we can represent any number

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In this example, Binary 1100 = (1 x 8) + (1 x 4) = 12
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To represent bigger numbers we add more binary digits (bits)
|
32,768 |
16,384 |
8,192 |
4,096 |
2,048 |
1,024 |
512 |
256 |
128 |
64 |
32 |
16 |
8 |
4 |
2 |
1 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
215 |
214 |
213 |
212 |
211 |
210 |
29 |
28 |
27 |
26 |
25 |
24 |
23 |
22 |
21 |
20 |
Hexadecimal
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Hexadecimal is a number system that is made up of 16 digits, 10 numbers (0-9) and 6 letters (A-F)
|
0 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
13 |
14 |
15 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
0 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
A |
B |
C |
D |
E |
F |
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Hexadecimal is referred to as a base-16 number system
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Each digit has a weight factor of 16 raised to a power, the rightmost digit is 1s (160), the next digit to the left 16s (161)
|
16s |
1s |
|
|---|---|---|
|
1 |
3 |
|
|
1 x16 |
3 x 1 |
= 19 |
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A quick comparison table demonstrates a relationship between hexadecimal and a binary nibble
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One hexadecimal digit can represent four bits of binary data
|
Denary |
Binary |
Hexadecimal |
|---|---|---|
|
0 |
0000 |
0 |
|
1 |
0001 |
1 |
|
2 |
0010 |
2 |
|
3 |
0011 |
3 |
|
4 |
0100 |
4 |
|
5 |
0101 |
5 |
|
6 |
0110 |
6 |
|
7 |
0111 |
7 |
|
8 |
1000 |
8 |
|
9 |
1001 |
9 |
|
10 |
1010 |
A |
|
11 |
1011 |
B |
|
12 |
1100 |
C |
|
13 |
1101 |
D |
|
14 |
1110 |
E |
Responses