# Binary & Logic

### How does a computer ***compute***? <a href="#how-does-a-computer-compute" id="how-does-a-computer-compute"></a>

Before the [**`digital`**](https://www.merriam-webster.com/dictionary/digital) computer, wheels and cogs were used in [**`analog`**](https://www.merriam-webster.com/dictionary/analog) calculating machines. These were clunky and required manipulation by hand. They were also slow.

![X-15 Analog computer via Wikimedia Commons](https://1200419583-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LKbpNQDFNJap9OTDSt6%2F-LKmB6Dl_tx0sQ2b6Yv-%2F-LKmNc4NWx3FdCnjSpYu%2FX-15_Analog_computer.jpg?alt=media\&token=8d75a0fc-72e9-4205-83f2-06bf80c72f5a)

Electricity travels very close to the speed of light (slowed by the physical wires transporting the electrons). If we can use electricity to add, subtract, multiply, and divide then we can quickly compute any combination of mathematics - close to the speed of light! **But how do we use flowing electrons to do math?**