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# Bits all the way down
Data representation · Binary numbers
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## Today
**We are learning to** every kind of data ends up as bits: a character becomes its code, and the code becomes 8 bits (A is 65, which is 01000001). A pixel is three codes, so 24 bits. The chain is always the same: data, then numbers, then binary.
- I can turn a character into its code and then into binary.
- I can work out how many bits a word or a picture takes.
- I can explain that all data becomes bits.
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## Why it matters
> You now know how text, pictures and sound become numbers, and how numbers become bits. What does the letter A actually look like inside the computer?
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💬 Discussion
## Predict
**The letter **A** has the code 65. How is it stored in the computer's memory?**
- 65
- A
- 01000001
- 1
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✍️ Activity
## Try it
{{embed: https://studio.learningwaypoints.com/tutorials/_playground-board/index.html?id=deck%2Fsystems%2Fdata%2Fbits-everywhere%2Fstep-2&code=widget%3A+bits%0Abits%3A+8%0An%3A+0%0A&fresh=1}}
[Open this step in the tutorial](https://studio.learningwaypoints.com/tutorials/systems/data/bits-everywhere/?full=step-2#step-2)
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✅ Check
## What happened?
* 01000001. The computer stores only bits: 65 = 64 + 1, so on 8 bits (one byte) the 64 and 1 places are 1.
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💬 Discussion
## Text and a pixel
Now count the bits in a pixel.
$$\text{A} \to 65$$
1) $65 = 64 + 1 \to 01000001$ — Binary on 8 bits: one byte.
2) $\text{yellow} \to 255, 255, 0$ — A pixel: three colour amounts.
3) $11111111\ 11111111\ 00000000$ — Each amount is one byte: 24 bits for the pixel.
4) $\text{data} \to \text{numbers} \to \text{bits}$ — Every kind of data follows the same chain.
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✅ Check
## Text and a pixel
**One pixel is three numbers (red, green, blue), each one byte. How many **bits** is one pixel?**
* Answer: 24
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✅ Check
## Find the mistake
**Sam works out how many bits the word cat takes. Click the line where it first goes wrong.**
```
1 How many bits does the word cat take?
2 c, a and t are three characters.
3 Each character is one bit.
4 So cat takes 3 bits.
```
* Answer: line 3
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✅ Check
## What does a byte mean?
**The byte **01000001** is in memory. What does it mean?**
- Always the number 65
- Nothing until it is decoded
- Always the letter A
- It depends on how a program reads it: A as text, 65 as a number, a dark shade as a colour amount
* Answer: It depends on how a program reads it: A as text, 65 as a number, a dark shade as a colour amount
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✍️ Activity
## Vary: one letter at a time
- **H to I:**
- **Lower case:**
- **Full colour:**
- **Silence:**
- **A space:**
[Open this step](https://studio.learningwaypoints.com/tutorials/systems/data/bits-everywhere/?full=step-4#step-4)
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✅ Check
## Bits in a word
**How many bits does the word **hello** take, at one byte a character?**
* Answer: 40
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✅ Check
## Bytes in a picture
**A 2 × 2 picture, three bytes a pixel. How many bytes?**
* Answer: 12
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✅ Check
## Sound samples
**Music often uses 65 536 levels a sample. How many bytes is each sample?**
- 2 (16 bits)
- 65 536
- 1 (8 bits)
- 4
* Answer: 2 (16 bits)
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✅ Check
## Byte to character
**As text, which character is the byte **01000010**?**
- 2
- B (66)
- A (65)
- b (98)
* Answer: B (66)
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✍️ Activity
## Make: a lower case letter
Then write your initials as bytes.
[Open this step](https://studio.learningwaypoints.com/tutorials/systems/data/bits-everywhere/?full=step-6#step-6)
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✅ Check
## Exit ticket
**Write the letter C as a byte. How many bits is the word Hi?**
* C = 67 = 64 + 2 + 1 = 01000011. Hi = 2 bytes = 16 bits.