# π’ Number Systems

Unit 2 β The internet | November 03# Do Now (in Classroom)

The letter `A`

is represented by `65`

in **ASCII**, the protocol used by most computers for text encoding.

American Standard Code for Information Interchange, a set of digital codes representing letters, numerals, and other symbols, widely used as a standard format in the transfer of text between computers.

Deep inside your computer, that `65`

is sent in binary. What is `65`

in binary?

## π― Learning Targets

I can use number bases, including binary, decimal, and hexadecimal, to represent and investigate digital data.

I can explain why hexadecimal is used to represent digital data.

## Review decimal & binary

Letβs write 15:

**Decimal:**

In **decimal**, we have 10 symbols: `0, 1, 2, 3, 4, 5, 6, 7, 8, 9`

.

15 in decimal:

1000 | 100 | 10 | 1 |
---|---|---|---|

Β | Β | 1 | 5 |

**Binary**

In **binary**, we have 2 symbols: `0, 1`

15 in binary:

8 | 4 | 2 | 1 |
---|---|---|---|

1 | 1 | 1 | 1 |

Binary numbers start to get very long, very quickly.

## Hexawhatnow?

Hexadecimal- base 16

**Hexadecimal**
In **hexadecimal**, we have 16 symbols: `0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, b ,c, d, e, f`

Wait, what?

15 in hexadecimal is `f`

.

4096 | 256 | 16 | 1 |
---|---|---|---|

Β | Β | Β | f |

## Notice!

- How many
`bits`

does it take to write 15 in decimal, binary, and hexadecimal? - Hex looks just like decimalβ¦until we try to write
**16**:

**Hexadecimal**

4096 | 256 | 16 | 1 |
---|---|---|---|

Β | Β | 1 | 0 |

Where have we seen **hex** before?

#E32173

Thatβs my favorite pink, Razzmatazz. Colors can be represented by mixing red, green, and blue. How much RGB is Razzmatazz?

Itβs 227 red, 33 g, and 115 blue. How do I know that?

Razzmatazz | R | G | B |
---|---|---|---|

Hex | E3 | 21 | 73 |

Decimal | 227 | 33 | 115 |