PyGCSE Python Lab

Floating Point — Binary Representation of Real Numbers

Understand how computers store real (decimal) numbers using floating point representation, including mantissa, exponent, normalisation, and precision trade-offs.

📚 Learning Steps

💡 Study Tips
  • • Read through at your own pace
  • • Try the interactive simulators hands-on
  • • Study the pseudocode — it appears in exams
  • • Quiz yourself before moving on

Step 1: Why Floating Point?

📖 Theory

Computers store everything in binary. While integers are straightforward, representing real numbers (numbers with fractional parts like 3.14) requires a different approach.

Fixed point representation uses a set number of bits for the integer part and a set number for the fractional part. This is simple but wastes bits — you can't represent very large or very small numbers efficiently.

Floating point solves this by letting the decimal (binary) point 'float' — similar to scientific notation in denary (e.g., 6.02 × 10²³).

🎯 Key Points
  • Fixed point: binary point is in a fixed position — limits range
  • Floating point: binary point can move — much wider range of values
  • Similar concept to scientific notation (e.g., 3.14 × 10²)
  • A floating point number has two parts: mantissa and exponent
  • Trade-off between range (exponent bits) and precision (mantissa bits)
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