Guides & How-tos · Worked examples · Real numbers

Science guides

Step-by-step how-tos, head-to-head comparisons and honest roundups — every guide worked through with current figures, then backed by a RECATOOLS calculator or AI-directory entry so you can act on it.

498 guides published 17 topic areas Latest guide Oct 2026

Tagged Chinese · 1 guide

All 498 Developer Tools 68 AI & ML 63 Finance 52 Home & Living 46 Chinese Culture 43 Science 40

A calligraphy brush on an ink stone in front of practice characters

Science 5 min

When yi (一) and bu (不) change tone, and why pinyin usually doesn't show it

一 is said yí before a fourth tone and yì before the others; 不 becomes bú only before a fourth tone; and a third tone r...

Nadia Rahim

Pub. 23 Sep