AQA 7517 4.5.4.4: Numbers with a fractional part
The free BugBot lessons that teach this point, a robot to try it on, and the past-paper questions that test it.
What it covers
Integers are not enough for a robot. Distances, voltages and headings have parts after the point. At GCSE every binary number was a whole number; this lesson stores fractions, first with a fixed binary point and then with a point that "floats", which is how a float in Python is stored.
- Binary fractions
- Fixed point
- Floating point: mantissa and exponent
- Normalisation
- Adding and subtracting floating point
- The robot's view
Or do it in the simulator, with tasks that mark themselves
Lessons that teach it
- A7.3 Fixed point and floating point Data representation
Binary fractions, mantissa and exponent, normalisation, and adding floating point numbers. - A7.10 Project: a secure sensor packet Data representation
Pack a distance reading into fixed point bytes with flags and a checksum, encrypt it with a one-time pad and send it by radio.
Try it on a robot
The task from A7.3 Fixed point and floating point, running here. Change the program and press Run.
The specification is AQA's own document; this page says which of our lessons teach point 4.5.4.4 and is not endorsed by the board.