Data Representation

Data representation

There are a number of very common needs for a computer, including the need to store and view data.

Computers use electrical signals that are on or off, so they have to see everything as a series of binary numbers. This data is represented as a sequence of 1s and 0s (on and off). All data that we want a computer to process needs to be converted into this binary format.

What is binary?

Binary is a number system that only uses two digits: 1 and 0. All information that is processed by a computer is in the form of a sequence of 1s and 0s. Therefore, all data that we want a computer to process needs to be converted into binary.

The binary system is known as a ‘base 2’ system. This is because:

  • there are only two digits to select from (1 and 0)
  • when using the binary system, data is converted using the power of two.

Task 1

What is binary?

How does it work?

What is the number base for binary?

Understanding denary

People use the denary (or decimal) number system in their day-to-day lives. This system has 10 digits that we can use: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.

The value of each place value is calculated by multiplying by 10 (ie by the power of 10). The first few place values look like this:


Working out the value of 1024

Thousands (1000s)Hundreds (100s)Tens (10s)Units (1s)
1 × 1000 +0 × 100 +2 × 10 +4 × 1

Task 2 (Use the information above and the video)

What is denary?

What is the number base for denary?

Exam questions

The memory of a computer contains data and information stored in binary.

  1. Explain why computers use binary ( 2 marks)
  2. Describe how information is stored in binary (3 marks)