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Sign & Magnitude

Computer Science: OCR A Level, topic 4.1.7

Sign and Magnitude

Sign and magnitude is a method of differentiating between positive and negative binary numbers

Most significant bit

Most significant bit

  • In sign and magnitude representation, the first bit in any byte is called the ‘most significant bit’ (MSB).
  • The MSB determines whether it is a positive or a negative number.
  • If the MSB is a 0, the number is positive.
  • If the MSB is a 1, the number is negative.
Example

Example

  • For example:
  • 00000100 represents the number 4
  • 10000100 represents the number -4

Test yourself on Sign & Magnitude

  • Which character do we set the MSB equal to if the number is positive?

  • The following number is written in sign and magnitude representation. What is its denary value?
    10000111

  • The following number is written in sign and magnitude representation. What is its denary value?
    00101011

  • What does MSB stand for?

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