πŸ”’ Number Systems

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?

🎯 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

Let’s 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!

Hexadecimal

4096 256 16 1
Β  Β  1 0

Where have we seen hex before?

#E32173

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

It’s 227 red, 33 g, and 115 blue. How do I know that?

Razzmatazz R G B
Hex E3 21 73
Decimal 227 33 115