[Feature] rule of third calculator

[gravelfreeman]

Problem or use case

Always nice to have this quickly when you want to try many numbers in a row.

Proposed solution

https://www.ruleof3.app/

Alternatives considered

No response

Area

New tool

Contribution

• I'm willing to submit a PR for this feature

[snapotter-hq]

Filed #787, thanks. Quick note: ruleof3.app is the proportion solver (rule of three), not the photographic rule-of-thirds grid, so I titled it that way to keep them apart. It'd be a client-only calculator, no upload.

[gravelfreeman]

Thank you so much! That was fast!