A-level Computing/AQA/Paper 2/Fundamentals of data representation/Binary number system/Binary fractions

Binary Fractions using Fixed Point

Fixed point is a method used to represent a fractional number in binary form. This means that it can be used to represent number such as 2 & 1/2 or 6 & 15/16. This section shows how fixed point can represent fractional numbers.

Assume we want to convert the binary code 11000110₂ into decimal using fixed point:

Step 1 Write out the decimal (or denary, if you prefer) equivalent as show: $8$ $4$ $2$ $1$ . $1/2$ $1/4$ $1/8$ $1/16$ 1 1 0 0 0 1 1 0

Step 2 Add the numbers together so in this case: 8+4+1/4+1/8 = 12 & 3/8