Book · Non-fiction, memoir and self-help
The Demon-Haunted World : Science As a Candle in the Dark
by Carl Sagan
Page count, estimated reading time and reading quiz: everything to know before you start The Demon-Haunted World : Science As a Candle in the Dark, and the Vread challenge to get to the end.
- Pages
- 537
- Reading time
- ≈ 9 h 40 min
- Checkpoints
- 15
- Genre
- Non-fiction
Free on iPhone and Android.
How long does it take to read The Demon-Haunted World : Science As a Candle in the Dark?
At 537 pages, The Demon-Haunted World : Science As a Candle in the Dark is a long book. Expect about 9 hours 40 minutes of reading to finish it, based on 250 words per page and an average reading speed of 230 words per minute. A fast reader will go quicker; a careful read (or reading in a second language) will take longer.
At 30 minutes a day, that is about 20 days of reading. At the median pace of Vread readers, 72 pages per reading day, it takes 8 reading days. For a book of this length (400 to 599 pages), Vread readers who finish it take a median of 5.3 days between the first and the last checkpoint (Vread Reading Barometer 2026).
- 30 minutes a day20 days
- Vread median pace (72 pp./day)8 days
Estimates; see the method at the bottom of the page.
Prove you read it
The Vread challenge: 15 checkpoints
- Checkpoint 1, page 36
- Checkpoint 2, page 72
- Checkpoint 3, page 107
- Checkpoint 4, page 143
- Checkpoint 5, page 179
- Checkpoint 6, page 215
- Checkpoint 7, page 251
- Checkpoint 8, page 286
- Checkpoint 9, page 322
- Checkpoint 10, page 358
- Checkpoint 11, page 394
- Checkpoint 12, page 430
- Checkpoint 13, page 465
- Checkpoint 14, page 501
- Checkpoint 15, page 537
In Vread, The Demon-Haunted World : Science As a Candle in the Dark is split into 15 checkpoints, one every 36 pages or so. At each checkpoint, a question covers the passage you have just read: a correct answer validates the step, and your progress moves forward like a training plan.
The challenge: validate all 15 checkpoints through to the last page. No giant quiz at the end, no summary to copy out: short questions along the way that prove the book was actually read. It also works as a reading quiz to check your understanding before a test.
Also available in French on Vread.
Illustrative example
What a checkpoint looks like
A short, precise question about the pages you have just read: a character, a place, a choice.
The answer is in the text: reply in the app.
This is not a question from The Demon-Haunted World : Science As a Candle in the Dark: to avoid spoilers, the real questions stay in the app.
Answer in the app, one checkpoint at a time.
Summary, quiz, reviews: frequently asked questions
How many pages is The Demon-Haunted World : Science As a Candle in the Dark?
How long does it take to read The Demon-Haunted World : Science As a Candle in the Dark?
Is there a quiz on The Demon-Haunted World : Science As a Candle in the Dark?
Where can I find a summary of The Demon-Haunted World : Science As a Candle in the Dark?
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Read The Demon-Haunted World : Science As a Candle in the Dark with Vread
Add the book to your library, read at your own pace in whatever format you use, and validate each checkpoint. Vread is free on iPhone and Android.
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