Activity Industry Sector
Engineering & Design

## Lecture 30min

### Activity Overview / Details

Computers think in numbers that are multiples of 2, especially 2 (binary), 8 (octal), and 16 (hexadecimal).

Binary is the base language of computers, since that is how they think as ones and zeroes (on and off), but for us to understand what they are saying it is best if we work using octal or even hexadecimal, since these are numbers large enough to comprehend.

Octal was used in early systems, but hexadecimal is preferred now since a hexadecimal number can be used to represent four binary digits. Put two hexadecimal digits together, and you have an eight-bit byte, which makes it easy to write computer code in hexadecimal format.

The problem with hexadecimal is that we only have 10 digits to work with using the decimal system- 0,1,2,3,4,5,6,7,8,9. For hexadecimal, we need six more digits! Where will we get them? Ask the students to brainstorm with you and come up with some new “digits” to use for hexadecimal numbering. You can use stars, hearts, clovers— whatever you want! Write them on the board.

Now ask the students how you would go about entering these new “digits” into a computer. Whoops! There aren’t any keys for them. Explain to the students that this is why computer programmers decided to use the letters A, B, C, D, E and F as the extra digits.

Show the video clip “Bits and Bytes”at this point.

Explain that the problem with using letters for numbers is the confusion it causes when it is difficult to tell whether they are numbers or words. This is why computer programmers begin a hexadecimal number with the prefix 0x, such as 0x4BC3. There are other designations for hexadecimal numbers, but 0x is the most used.

Show the video “What is Hexadecimal”to reinforce the concepts