Read the table once, then close the page and recite each row from memory. If you stumble on ratio or EXIF rows, open the linked guide the same day.
| Topic | Remember | Why it matters on the exam |
|---|---|---|
| Binary → decimal | Sum powers of two where bit = 1 | Small conversions appear without calculators |
| Decimal → binary | Subtract largest power of 2 repeatedly | Show structure to avoid off-by-one bits |
| n bits | 2ⁿ values; max unsigned = 2ⁿ − 1 | Capacity and overflow stems |
| Bit vs byte | 8 bits = 1 byte; label units | Mbps vs MB traps |
| Compression ratio | Original : compressed (100:25 = 4:1) | Do not confuse with percent saved (75%) |
| RLE | Count + symbol for runs | Fails on random noise |
| Photos | JPEG lossy; PNG lossless | Scenario “best format” MCQs |
| Audio | MP3 lossy; FLAC lossless | Streaming vs archive stories |
| Legal / medical text | Lossless only | Integrity beats size |
| Metadata | Data about data; EXIF may include GPS | Privacy prompts |
| Filtering vs sorting | Filter = keep rows; sort = reorder | Information extraction |
| Correlation | Moves together ≠ causes | Societal-impact writing |
| 3 Vs | Volume, velocity, variety | Big-data definitions |
| PII + re-ID | Fields can deanonymize tables | Ethics and policy items |
Five traps that repeat
Trap 1: Treating binary 101 as one hundred one instead of five. Trap 2: Forgetting overflow after a correct conversion. Trap 3: Answering 75% when the question asked for 4:1. Trap 4: Picking JPEG for text screenshots. Trap 5: Claiming causation from correlation alone.
Next steps after the table
Run the eighteen-question Unit 2 quiz timed, then conversion practice for any miss tagged “binary.” Return here the morning of practice tests until every row feels automatic.
Worked compression example
A yearbook committee exports 200 MB of photos. After JPEG batch processing, the folder is 50 MB. Ratio = 200:50 = 4:1. Percent saved = (150÷200)×100 = 75%. If a stem only asks ratio, do not answer 75% unless it asks for percent saved.
ASCII and byte quick example
The word “Hi” needs two bytes in simple ASCII: 72 for H and 105 for i. A stem that says “two characters, one byte each” is testing bytes, not bits—sixteen bits total unless Unicode is mentioned.
Metadata scenario cue
Posting a team photo with EXIF GPS still attached can reveal the gym location even when the caption says nothing about place. Compression does not remove metadata; stripping EXIF is a separate privacy step.