### Movie Case Study

The scene that you just saw shows how Mark Watney (played by Matt Damon) is stranded on Mars (planet). First, he builds a binary message-sending device that succeeds in regaining communications with NASA. After that, he improves his device so he can send more complicated messages. and now he communicates with NASA using the system of hexadecimal.

In this blog, Learning Perspectives will explore the meaning of hexadecimal.

Hexadecimal is a numbering system. It has a base of 16 number systems. Hexadecimal numbers are 0-9 and then A-F is used. Hexadecimal is a way of converting into binary numbers. In the binary system, each byte consists of 8 bits.

Mark Watney is able to find an ASCII table on another laptop and device this communication to exchange complex dialogues.

#### ASCII Table

Each stick shows decimal, octal, hex, and character values. One hexadecimal can show the arrangement of four binary digits. Two hexadecimal digits can represent eight binary digits or a byte.

So NASA sends him the codes 48, 4F, 57, 41, 4C, 49, 56, and 45. When Watney starts converting them, he finds out that it means ‘How Alive’? Later, he writes a long message which can be read through the cameras by them.

You can try converting it yourself, look at the above table and see the 11th column, it says 48 as H, 4F as O, and so on.