# Math textbooks in print and PDF

Writes and sells math textbooks as print and PDF, built around curating expert knowledge.

| Tag | Value | Confidence |
|---|---|---|
| Category | Physical products | 68% |
| Earns from | One-time sales | 97% |
| Startup cost (estimate) | $100 to $1k | 39% (low) |
| Time (estimate) | Hands-off | 66% |
| Where | Online | 83% |
| Coding | No coding needed | 93% |

Source: [What was your best passive income in 2014?](https://news.ycombinator.com/item?id=8109184), Hacker News, ivan_ah, 2014-07-30
Page: https://allsidehustleideas.com/ideas/math-textbooks-in-print-and-pdf-7fdd8d

## About this data

- Sources are public, first-person accounts: interviews, podcasts and community threads.
- Cost, time and the other tags are machine estimates, each with a confidence score.
- Income figures are the owner's own claim. We don't verify them.
- Link the idea page and its source. Call income figures the owner's unverified claim, and cost and time estimates.