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Hướng dẫn, bài học và mẹo để tận dụng tối đa các công cụ trực tuyến miễn phí. 120 bài viết.
120 articles — page 1 of 5
What Does a Broken Link Actually Cost? The Answer Has Three Parts.
Broken links waste crawl budget, interrupt authority flow, and degrade user experience. A JAMA study found 50% of cited links go dead within 5 years. Here is what to do.
The Acre Was the Amount of Land One Man and Eight Oxen Could Plow in One Day. Edward I Made It Official in 1305.
The acre was not derived from mathematics — it was the daily output of a plow team. Edward I's 1305 statute fixed it, and the US still uses it today.
The Blank Page Problem Is Not About Writing. It Is About Structure.
Cognitive load theory explains why starting is hard. Here is what an outline actually does to your working memory, and why structure decisions are cheapest before drafting.
The BMR Formula Used for 65 Years Was Overestimating Calories. A 1990 Revision Fixed It.
Harris and Benedict published their BMR formula in 1919. It went unrevised for 65 years. The Mifflin-St Jeor revision in 1990 corrected a 5-8% systematic overestimate.
The US Navy Replaced Lab Tests With a Tape Measure in 1984. The Method Still Works.
Hodgdon and Beckett's 1984 Naval Health Research Center formula estimates body fat to within 3-4%. Here is how it compares to expensive lab methods.
Trimming a Video Is Not the Same as Cutting It. Here Are the Differences and Why They Matter.
Trimming removes from the edges. Cutting removes from the middle. Splitting creates two clips. Here is what each video editing operation actually does and when to use each.
Knots Come from a Rope Thrown Overboard in 1600. Aviation Still Uses Them Because Nobody Can Afford to Switch.
Knots were measured by counting knotted rope intervals on 16th-century ships. Here is why that unit survived into jet aviation, and why Mach 1 is not a fixed speed.
Simple Interest Is Not Just the Simpler One. It Is the One Borrowers Should Usually Want.
Simple interest only accrues on the original principal, never on accumulated interest. Here's why that makes it the better deal for borrowers, and when the difference matters.
What Actually Happens in the 200 Milliseconds Before the HTTPS Padlock Appears
The HTTPS padlock appears in under 200ms. Before it does, cryptographic identities are verified and keys are exchanged. Here's exactly what happens, step by step.
Dani's Commute Cost $6,240 a Year. She Almost Turned Down a Remote Job for $8,000 Less.
A 47-mile daily commute at 28 MPG costs over $6,000 a year in fuel alone. Here's why fuel costs are consistently underestimated and how to calculate them accurately.
Your Electricity Bill Is $1,500 a Year. Most of It Comes From Two Things You Probably Ignored.
A 1,500-watt space heater costs $61 a month to run 8 hours a day. Heating and cooling are 45% of the average electricity bill. Here's how the numbers work.
Bank of America Sent 60,000 Unsolicited Credit Cards to Fresno in 1958. Here Is What the Minimum Payment Became.
Bank of America's 1958 Fresno Drop created revolving credit. Understanding minimum payment math shows why debt lasts decades longer than it should.
Fitness Trackers Overestimate Calorie Burn by Up to 93 Percent. Here Is Why the Formula Has Always Had That Problem.
The MET formula behind calorie burn estimates was built on a 40-year-old 70kg man. Stanford found trackers off by 27-93%. Here is what that means for your workouts.
Your Font Is Not a Font: What Unicode Actually Sends When You Post in Bold on Instagram
Styled text on social media uses Unicode Mathematical Alphanumeric Symbols, not fonts. Here is why that distinction matters for search, accessibility, and copy-paste.
Steve Wilhite Created the GIF in 1987 to Work on 2,400 Baud Modems. Here Is Why It Is Still Everywhere.
The GIF was invented in 1987 as a file size solution for dial-up networks. Here is how it became the dominant format for reaction content on the modern web.
PDF Owner Passwords Restrict Printing and Editing. They Were Never Designed to Actually Enforce Those Restrictions.
PDF owner passwords restrict printing and editing but are only honored by cooperative viewers, not enforced by encryption. Here is what that means in practice.
170 Countries Collect a Value-Added Tax. The US Does Not. Here Is How the System Actually Works.
A French finance inspector invented VAT in 1954 to stop cascading taxes. Over 170 countries adopted it. Understanding it matters for any cross-border transaction.
She Had Three Screenshots and a Confluence Page. Here Is Why She Combined Them Into a GIF.
Stacking screenshots requires scrolling. Video requires a click. A looping GIF from images shows a complete sequence with no user action. Here is how to do it well.
She Posted the Bug as an MP4. Half the Team Did Not Watch It. Here Is Why GIF Works Better in Slack.
MP4 is technically superior to GIF, but GIFs autoplay without interaction in Slack, email, and documentation tools. Here is when and how to convert effectively.
Google's 2009 JavaScript Compiler Renamed Your Variables. Here Is Why That Is Legal and Why It Makes Code Unreadable.
JavaScript minification renames variables, removes dead code, and inlines functions. Here is what makes JS minification different from CSS minification and how source maps fix debugging.
Flat JSON Converts to CSV Without Problems. Nested JSON Does Not. Here Is What Breaks.
CSV is a flat format. JSON supports nested objects and arrays. Here is what actually happens to nested data during conversion and how to handle it before you start.
From Red Pens to Algorithms: The Stakes Behind Text Comparison
Before automated diffing, lawyers spent hours spotting contract changes by hand -- and missed some. Here's the algorithm behind text comparison and why it matters.
AI Enhancement Does Not Restore Your Old Photos. It Fabricates What It Thinks Should Be There.
AI image enhancement synthesizes photorealistic detail that was never captured. Here is what that means for legal, forensic, scientific, and personal use.
The Americans With Disabilities Act Was Passed in 1990. Online Video Did Not Have to Follow It for Another Two Decades. Here Is Where Things Stand Now.
Online video accessibility law has expanded significantly since 1990. Here is what ADA, Section 508, and the CVAA require for video transcripts and captions.