In this section you will be introduced to **number bases** by considering number systems you encounter every day, for example the conversion of seconds to minutes or hours to days.

We’ll look at the use of **binary** and **hexadecimal** systems within the computer, including the use of ASCII and Unicode to represent **characters and symbols** and RGB values used to represent **colours** in web design and you’ll learn how to convert numbers between bases 2, 10 and 16. We’ll also consider the importance of base two (binary) in calculating available memory from the **width of the** **address bus**, the **size of memory modules** in powers of 2 and give an explanation of **bits, bytes, kilobytes, IP addressing **and** subnet masking**.

**Arithmetic** in number bases 2 and 16 will include addition and subtraction applying 2’s complement. We’ll also look briefly at multiplication and division and factors affecting the accuracy of calculations.

**Logical operators** will be presented using both words and symbols for gates. We’ll look at some practical applications, including the use of **truth tables** to simplify code or circuitry,** logic gate diagrams** to show equivalencies, using **masks** to change data from lower to upper case or **determining a network address** from an** IP address** and **subnet mask**.

**Next: Number Bases**