1. GCSE COMPUTER SCIENCE
Topic 3 - Data
3.1 Binary

2. Binary
What is binary?
Binary is used to represent all data on a computer
This includes numbers, text, sound, images etc
Binary also represents program instructions

3. Humans use it because we have 10 fingers
Denary
The denary number system (also known as decimal) uses 10 symbols (0-9) to represent numbers. It is a base-10 number system
Humans use it because we have 10 fingers

4. Circuits
Computers don’t have fingers, they have circuits. These circuits can be in one of two states, on or off. So they use a base-2 number system.
On = 1
Off = 0
Transistors are switches that are used to make circuits, in their off state they represent a 0 and in their on state they represent a 1.

5. We need 8 volunteers to stand at the front facing the class.
Counting in Binary Part 1
We need 8 volunteers to stand at the front facing the class.
Each place in a binary number has a value. These go up in multiples of 2.
128 64 32 16 8 4 2 1
Sitting = 0
Standing = 1

6. Start by writing out the place values:
Denary to Binary 65
Start by writing out the place values:
128 64 32 16 8 4 2 1
Then write 1s underneath the place values that add up to the denary number.

7. Binary to Denary
Start by writing out the binary number
128 64 32 16 8 4 2 1
64+8+2=74
Then write the place values above each binary number
Finally, add up each number that has a 1 in the place value