Storage Examples in CS Thinking

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Storage.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in CS Thinking.

Concept Recap

Storage is the part of a computing system that keeps data over time, even when the power is turned off. Files, photos, apps, and operating systems all live in storage devices such as SSDs, hard drives, and flash memory.

Memory is the desk you are working on right now. Storage is the filing cabinet that keeps your work after you leave.

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How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Storage is about persistence: the data stays there after the program stops running.

Common stuck point: Storage is not the same as memory. Memory is temporary working space; storage is long-term data keeping.

Sense of Study hint: When comparing storage needs, count how many items you have and estimate how many bytes each one uses. Then compare that to the device capacity.

Common Mistakes to Watch For

Before you work through the examples, skim the mistake guide so you know which shortcuts and sign errors to avoid.

Binary Mistakes

Worked Examples

Example 1

medium
A song is 5 MB. Album of 12 songs. How many MB for the album, and how many albums fit on a 1 GB player? (1 GB = 1024 MB)

Answer

60 MB;  17 albums60\text{ MB};\;17\text{ albums}

First step

1
Album size = 12×5=6012 \times 5 = 60 MB.

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Example 2

medium
A photo album of 1200 photos at 3.5 MB each: total in GB? (1 GB = 1024 MB)

Example 3

hard
A sensor records 200 bytes every 10 seconds. How many MB does it produce per day? (1 MB = 102421024^2 bytes)

Example 4

hard
Compression reduces a 10 GB log to 1.5 GB. What is the compression ratio (original / compressed) and percent savings?

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

easy
How many bytes are in 1 kibibyte (1 KB as used in this curriculum)?

Example 2

easy
Which is bigger: 1 GB or 1 TB?

Example 3

easy
Does data in storage survive after the power is turned off? Yes or no.

Example 4

easy
How many MB are in 1 GB?

Example 5

easy
Which keeps your files after you close a program: RAM or storage?

Example 6

easy
How many bytes are in 2 KB?

Example 7

easy
Deleting an app always removes all of its saved data. True or false?

Example 8

easy
How many KB are in 1 MB?

Example 9

medium
You store 500 photos, each 4 MB. How much storage is needed, in MB?

Example 10

medium
A 3 GB video and a 1024 MB photo set: what is the total in GB? (1 GB = 1024 MB)

Example 11

medium
A drive holds 256 GB. How many MB is that? (1 GB = 1024 MB)

Example 12

medium
How many photos of 5 MB each fit in 1 GB of free space? (1 GB = 1024 MB)

Example 13

medium
Text file of 2000 characters at 1 byte per character: how many bytes, and is that under 2 KB?

Example 14

medium
Backing up 8 GB of data over a link that copies 1 GB per minute takes how many minutes?

Example 15

medium
You have 100 GB free and want to store a 0.1 TB game. Does it fit? (1 TB = 1024 GB)

Example 16

medium
A song is 4 MB. How many songs fit on a 2 GB player? (1 GB = 1024 MB)

Example 17

medium
A 0.5 GB folder and a 256 MB folder: total in MB? (1 GB = 1024 MB)

Example 18

challenge
A camera shoots 12 MB photos at 30 per second of burst. How much storage, in GB, does 60 seconds of burst use? (1 GB = 1024 MB)

Example 19

challenge
Explain why a '500 GB' drive often shows less usable space to the user.

Example 20

challenge
A log grows 50 MB per day. Starting empty, after how many whole days does it first exceed 1 GB? (1 GB = 1024 MB)

Example 21

easy
How many bytes are in 4 KB? (1 KB = 1024 bytes)

Example 22

easy
Which is bigger: 1 MB or 100 KB? (1 MB = 1024 KB)

Example 23

easy
How many KB are in 5 MB? (1 MB = 1024 KB)

Example 24

easy
Which storage type is typically faster: SSD or HDD?

Example 25

easy
A photo is 3 MB. How many bytes is that? (1 MB = 1024 KB, 1 KB = 1024 bytes)

Example 26

easy
True or false: closing a browser deletes the websites you visited from your storage forever.

Example 27

medium
A drive has 500 GB total, 320 GB used. What percentage is free?

Example 28

medium
A camera produces 8 MB photos. How many photos fit on a 4 GB card? (1 GB = 1024 MB)

Example 29

medium
Video at 25 MB per minute. How much storage for a 90-minute video, in GB? (1 GB = 1024 MB)

Example 30

medium
A 2 TB drive has 1.5 TB free. How many GB is free? (1 TB = 1024 GB)

Example 31

medium
A database table stores 50,000 records at 200 bytes each. How many MB does it occupy? (1 MB = 1024 KB; 1 KB = 1024 bytes)

Example 32

medium
A backup transfers at 50 MB per second. How long to back up 30 GB? (1 GB = 1024 MB)

Example 33

medium
A 16 KB block on disk stores small files. A file of 2 KB occupies how much disk space due to block allocation?

Example 34

medium
A laptop has 8 GB RAM and 512 GB SSD. Which holds your saved documents when off?

Example 35

medium
A 4K video uses 7 GB per hour. How many hours fit on a 256 GB SD card?

Example 36

medium
A photo at 5 MB compresses to 1 MB with JPEG. How many compressed photos fit in 100 MB?

Example 37

hard
A 1 TB drive is advertised using decimal (1 TB = 101210^{12} bytes), but the OS reports binary (1 TiB =240= 2^{40} bytes). Show in GiB how much the OS reports for 1 TB.

Example 38

hard
A RAID-1 mirror duplicates data on 2 drives. Two 4 TB drives in RAID-1 give what usable capacity?

Example 39

hard
A log file grows by 75 MB per day. After how many full days does it first exceed 2 GB? (1 GB = 1024 MB)

Example 40

hard
A user has 30 GB of photos and a cloud plan with 2 GB free. To upload everything, how many GB of paid storage do they need to add at minimum?

Example 41

challenge
A backup strategy keeps 7 daily, 4 weekly, and 12 monthly snapshots. Each is 50 GB. What is total snapshot storage (worst case, no deduplication)?

Example 42

challenge
A SSD is rated 600 TBW (total bytes written). If a user writes 100 GB per day, after how many years does the SSD reach its rated endurance? (Use 1 TB = 1000 GB, 365 days/year.)
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Background Knowledge

These ideas may be useful before you work through the harder examples.

computing systembits bytes