Practical guides, how-tos and comparisons to get the most out of our free online tools.
Average the parents' heights, shift by a sex constant, and you have a target height. The honest part is what comes next: the published prediction interval is about ±4 inches, wide enough to cover most of the adult population. Here is the formula, the interval, why bone age does better, and why children keep out-growing the target.
Sofia Nunes · 14 min read
The twelve tropical zodiac dates, their elements, and the reason the boundary between two signs falls on a slightly different day each year.
Antonio Delgado · 4 min read
Your sun sign comes from the date, your moon sign from the Moon's position, your rising sign from the exact time and place. Here is what separates the three and why birth time matters.
Antonio Delgado · 4 min read
Frame size exists because height alone does not fix skeletal mass, and the published methods are crude proxies with real cut-offs. The bigger story is the ideal-weight formulas: four of them, all built for drug dosing rather than health, disagreeing by up to 27 lb at the same height.
Sofia Nunes · 12 min read
The correction factor says how far one unit of insulin moves glucose, and the classical estimate is 1800 divided by the total daily dose in mg/dL — or 100 divided by it in mmol/L. Those are the same rule, and here is the arithmetic that proves it, plus why stacking is the error that actually hurts.
Sofia Nunes · 10 min read
The ratio says how many grams of carbohydrate one unit of insulin covers, and the usual starting estimate is 500 divided by the total daily dose. Here is where that number comes from, how sharply it moves across daily doses, why a 450 version exists, and the three things it quietly assumes.
Sofia Nunes · 10 min read
High blood glucose pulls water out of cells and dilutes the sodium in it, so a measured sodium in a hyperglycaemic patient reads lower than the real one. Here is the correction, both of the published factors, a case where they disagree by 4 mmol/L, and the different problem that lipids cause.
Sofia Nunes · 10 min read
Repeating number sequences have a fixed set of meanings in modern numerology. Here is the full table from 000 to 999, where the idea comes from, and why we notice them.
Antonio Delgado · 4 min read
The life path number reduces your full birth date to a single digit. Here is the exact method, the two rules people get wrong, and what the tradition says each number means.
Antonio Delgado · 5 min read
Five of six markets index the permitted increase to a published statistic, and each names a different one. The arithmetic is universal: on a $1,500 rent, ten years at a 1 percent index leaves you 25.38 percent below a market that grew 4 percent.
Camille Laurent · 16 min read
Milligrams per kilogram is one multiplication, and that is exactly why it fails: the documented errors are unit slips, misplaced decimal points and the wrong body weight, not hard maths. Here is the arithmetic done properly, the three body weights that give three different answers, and what body surface area changes.
Sofia Nunes · 13 min read
No monthly payment means the balance compounds instead of amortising. On $160,000 drawn against a $400,000 home, the debt passes the value in 11.68 years if prices stay flat — and reaches $714,857 by year twenty.
Camille Laurent · 14 min read