# That Blue Square Thing

## Computer Science GCSE

Note: this page deals with the old Edexcel GCSE (grades A-G) which no longer exists. I'm keeping it as an archive and because a number of the resources will still apply to newer (grades 1-9) courses. The AQA GCSE CompSci pages deal with a current course.

### Real Binary Numbers

Real numbers are decimal numbers. They can be anything from 1.5 to pi. In computing we generally use Float data types to store real numbers.

You need to know how real numbers are stored in binary (which is tricky as there's no decimal point in binary!) and how to convert real binary numbers to denary. Real binary numbers - the key points you need to know Converting real binary numbers - how to convert binary real numbers

As usual, make sure you're able to deal with 8-bit binary numbers for any conversions.

#### Revision exercises

Real numbers using binary are really quite hard to deal with.

The key points to remember if you're asked to explain how they work are:

• made up of sign, exponent and mantissa
• the exponent tells you how many places to move the dp
• the mantissa has the number without the dp

Make sure you can deal with basic conversions using real numbers. Real binary number revision exercises - conversion exercises Answers