# 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:

Thousands | Hundreds | Tens | Units |

(1000s) | (100s) | (10s) | (1s) |

Working out the value of 1024

Thousands (1000s) | Hundreds (100s) | Tens (10s) | Units (1s) |

1 | 0 | 2 | 4 |

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.**

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