# Hourglass — Time sums Puzzle | Mathallery

Source: https://mathallery.com/games/hourglass/

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# Hourglass

Time sums · 30 levels

Boil an egg for exactly 9 minutes with a 4 and a 7.

## How to play

- Tap a glass to flip it (a half-run glass flips with its sand). Next ⏩ jumps to the moment a glass runs out.
- You can only act at the start and at those moments: flip glasses, put the egg in, take it out.
- Boil the egg for exactly 🥚 minutes and serve it by ⏰. Later levels limit your flips ↻.

The egg doesn't have to go in at the start: a 3 and a 5 make 2 minutes. And a glass flipped halfway runs for exactly as long as it has already run.

[Open Hourglass](https://mathallery.com/#/play/hourglass/1)

Teeter, Tint and Echo Heist are free starters. Other games unlock through earned game choices or permanent packs. Your progress stays in the browser; optional sign-in saves it to your website account.