# The Lost Key by Melinda Thielbar — resale value

Source: JunkPal price guide — https://junkpal.ai/products/the-lost-key-melinda-thielbar-ol20461191w

**The Lost Key by Melinda Thielbar** — resale value from real closed eBay sales.

Live listings and the full sold-price history are on the page: https://junkpal.ai/products/the-lost-key-melinda-thielbar-ol20461191w

Values are medians of real closed eBay sales, updated 2026-06-19. They are estimates for reference, not offers or appraisals — condition, completeness and edition move them a lot, so compare against the sold listings before pricing anything.

## Check the market

- [Sold listings on eBay](https://junkpal.ai/api/go?to=https%3A%2F%2Fwww.ebay.com%2Fsch%2Fi.html%3F_nkw%3DThe%2520Lost%2520Key%2520by%2520Melinda%2520Thielbar%26LH_Sold%3D1%26LH_Complete%3D1%26mkcid%3D1%26mkrid%3D711-53200-19255-0%26siteid%3D0%26campid%3D5339166094%26toolid%3D10001%26mkevt%3D1%26customid%3Dmd-sold&p=md-sold) — the closed sales these medians are computed from
- [Live listings on eBay](https://junkpal.ai/api/go?to=https%3A%2F%2Fwww.ebay.com%2Fsch%2Fi.html%3F_nkw%3DThe%2520Lost%2520Key%2520by%2520Melinda%2520Thielbar%26mkcid%3D1%26mkrid%3D711-53200-19255-0%26siteid%3D0%26campid%3D5339166094%26toolid%3D10001%26mkevt%3D1%26customid%3Dmd-live&p=md-live) — what sellers are asking right now

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## Details

| Field | Value |
| --- | --- |
| UPC / EAN | 0761369422 |
| Brand | Melinda Thielbar |
| Published | 2010 |
| Publisher | Lerner Publishing Group |
| Pages | 48 |
| Editions | 7 |
| Category | Mathematics |

## The Lost Key resale value

**The Lost Key** by Melinda Thielbar (2010). Across 7 editions. Used-book value depends heavily on edition (first printing vs. reprint), condition, dust jacket, and whether it's signed. First editions and out-of-print titles command the biggest premiums.

### What drives the price

First editions/first printings, intact dust jackets, signatures, and unmarked pages are the top value drivers. Book-club editions and later reprints are worth far less.

## FAQ

**Is this 2010 math book still in demand for students?**

Yes, as a published work from Lerner Publishing Group, it continues to be relevant for mathematics education.

**What is the ISBN for this specific edition?**

The ISBN for The Lost Key is 0761369422.

**How many pages does this book contain?**

This edition of The Lost Key contains 48 pages.

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Full price guide: https://junkpal.ai/products/the-lost-key-melinda-thielbar-ol20461191w
How these values are computed: https://junkpal.ai/methodology
Cite as: "JunkPal price guide value as of 2026-06-19, based on real sold listings (junkpal.ai)"