Negative Numbers

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Negative Numbers

• Lecture L2.3
• Section 2.4

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Negative Numbers
Subtract by adding
73 -35 38
73 65 138
10s complement
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Negative Numbers
10s complement Subtract from 100
Take 9s complement and add 1
100 -35 65
99 -35 64 1 65
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Negative Numbers
2s complement Subtract from
Take 1s complement and add 1
100000000 01001101 10110011

11111111 -01001101 10110010 1 10110011
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Finding 2s Complement
0 1 0 1 1 0 0 0
0
0
0
1
0
1
0
1
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Negative NumberTake 2s Complement
7510 4B16 01001011 -7510 B516 10110101
FF -4B B4 1 B5
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Negative NumberTake 2s Complement
110 0116 00000001 -110 FF16 11111111

12810 8016 10000000 -12810 8016 10000000
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Signed Numbers
4-bit 8H -8 to 7H 7 1000 to 0111
8-bit 80H -128 to 7F 127
16-bit 8000H -32,768 to 7FFFH 32,767
32-bit 80000000H -2,147,483,648 to
7FFFFFFFH 2,147,483,647
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Questions
What is the twos complement of 00101100? What
hex number represents the decimal number -40?