Guides & How-tos · Worked examples · Real numbers

Do it right, with real numbers

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.

510 guides published 17 topic areas Latest guide Oct 2026

All 510 Developer Tools 69 AI & ML 63 Finance 52 Home & Living 49 Chinese Culture 44 Science 43

The exposed mechanism of an old mechanical meter on a black background, showing a numbered counter wheel, a graduated dial and brass gears.

AI & ML 6 min

Two providers charge a toll for your prompt cache. One charges rent.

All three major providers price a cache read at a tenth of normal input, so caching looks like the same deal everywhere....

Kenji Tanaka

Pub. 3 Sep

A white observatory dome on a sandy ridge at night, lit from below, with the Milky Way arching across a deep blue star field above it.

Science 8 min

Leap seconds end on 20 May 2027, and the Earth has already turned around

The committee that has inserted 27 leap seconds since 1972 is proposing to stop, and to let clock time drift up to an ho...

Nadia Rahim

Pub. 3 Sep

A dense overlapping spread of Indian one-hundred-rupee banknotes filling the frame, the Reserve Bank of India lettering and Gandhi portrait repeating across them.

Finance 8 min

The South Asian number ladder that no two countries share

Lakh and crore are usually presented as one regional system continuing upward into arab and kharab. Take the ladder to f...

Sarah Chew

Pub. 3 Sep

Red network cables plugged into a handful of ports on a black rack-mounted switch, most of the numbered ports beside them empty.

Developer Tools 7 min

MCP deleted the handshake every tutorial teaches

The Model Context Protocol revision of 28 July 2026 removed the initialize handshake, the session header and the server'...

Kenji Tanaka

Pub. 2 Sep

Gloved hands holding four capped blood collection tubes against a plain pale background, a masked clinician partly visible at the edge of the frame.

Health & Wellness 7 min

The kidney formula in your drug label came from seven data points

The 1976 equation that still decides anticoagulant doses was fitted to seven averaged points, drawn from 249 men after h...

Amelia Wong

Pub. 2 Sep

Trays of metal letterpress type seen from above, individual raised letter blocks sorted into red compartments, the nearest ones in sharp focus.

Chinese Culture 6 min

The letter Chinese passports will not print

Hanyu Pinyin has a letter no Chinese travel document will print: ü. The rule that replaces it is two rules, not one — 吕...

Eva Chin

Pub. 2 Sep

A wall-mounted year planner photographed in shallow focus, columns of printed date numbers running down the sheet with several rows blocked out in yellow highlighter.

AI & ML 9 min

One cloud answers with a different model instead of failing

Every hosted model has a date after which it stops answering. Almost everywhere that is an error you can see in your log...

Kenji Tanaka

Pub. 2 Sep

A Chinese calligraphy practice book lying open on a pale desk, its ruled grid squares each holding one traditional character in regular script, with a hand at the right holding a brush pen above the page.

Chinese Culture 10 min

花 has seven strokes, and eight, and ten

Count it on the mainland and you get seven. Taiwan's education ministry says eight. A 五格 name reading says ten — a num...

Eva Chin

Pub. 2 Sep

The wave-patterned Portuguese paving of Senado Square in Macau, with the white Leal Senado building on the left and a pink colonial-era building on the right under an overcast sky.

Chinese Culture 7 min

The 226-page book that decides how Macau spells your name

Macau has a statutory table for romanising Cantonese names, running 226 pages of the 1985 gazette. Hong Kong has no rule...

Eva Chin

Pub. 2 Sep

Close-up of the round metal keys of an antique typewriter in black and white, showing the letters A, S, D, Z and X beside a shift-lock key labelled in Spanish.

Cybersecurity 7 min

The lookalike domain that is blocked on .com and shown on .ru

The famous all-Cyrillic apple.com impersonation was patched in 2017 and the matter filed as closed. Both major browsers...

Kenji Tanaka

Pub. 1 Sep

A vertical pink neon sign spelling three Chinese characters, glowing against a dark city street at night with blurred lights behind it.

Chinese Culture 6 min

Most 火星文 converters are running the same copied file

Feed the same characters to several Martian-text converters and most agree exactly. That looks like a standard. It is on...

Eva Chin

Pub. 1 Sep

A Chinese calligraphy practice sheet printed with traditional characters in a grid, with a black ink stone, a brush and two small jade water droppers resting on top of it.

Chinese Culture 6 min

Why a converter turns a toast into an obscenity

干杯 converts to 乾杯 correctly. Insert one character and 干了一杯 comes back 幹了一杯, which reads as an obscenity in T...

Eva Chin

Pub. 1 Sep

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