MARS
size, distances and time — computed from rotation, orbit and mass
THE SOLAR SYSTEM
eight planets · size, distance, year and day
THREE HAND STITCHES
backstitch · running stitch · whipstitch — what shows on the face and what the thread does underneath
DEVELOPMENTAL MILESTONES · YEAR ONE
2, 4, 6, 9, 12 months per the CDC checklists (2022 revision): 59 milestones that at least 75% of children reach by each age
DEVELOPMENTAL MILESTONES · YEAR TWO
15, 18, 24 months per the CDC checklists (2022 revision): 41 milestones that at least 75% of children reach by each age
SIZE CHARTS
shoes, tops, bottoms — and a centimetre under every grid
STAIN REMOVAL
five stain classes and the method for each — per publication H.E. 2-840 of the University of Kentucky Cooperative Extension
AI MILESTONES
ten tasks, the year of each, the system, the figure — and the human it was measured against
AUDIO FORMATS
who published each standard, when, what it does to the sound, and how many bits per second it allows
BIG-O NOTATION
the seven growth classes: how many steps, how long they take and how far each one lets you go
BINARY COUNTING
five doubling cards build every number from 0 to 31 — exactly the way every computer counts
THE CRON EXPRESSION
the five schedule fields: what each one means, what values it takes, and how to read stars, lists and steps
THE EXIT STATUS
One byte from a command to the shell: what the standard assigns in it, what it leaves to the system — and why “128 + signal number” is nowhere in the standard
A NUMBER IN 32 BITS
sign, exponent and significand: what actually sits in a float and what does not
GIT WORKING AREAS
four areas · the command that moves code between them
IPv6 ADDRESS NOTATION
eight groups of sixteen bits, the double colon, and one canonical spelling out of thousands
LOGIC GATES
Seven digital-logic symbols — and how to build six of them from a single element, NAND
MARKDOWN SYNTAX
headings, emphasis, lists, links and code per the CommonMark 0.31.2 specification — the core all dialects share
MEDIA TYPES
2322 registered subtypes under 11 top-level types, and how to read one you have never seen
THE FLAGS OF OPEN()
FIVE flags of creating a file — and why O_CREAT|O_EXCL is not a faster check but a check and a creation joined into one indivisible act
${…}: TRIMMING BY PATTERN
The sign says from which end to cut and doubling it says how much: from the same path the same pair of patterns takes away either one character or fifteen
THE ORDER OF REDIRECTIONS
Redirections are done from left to right, and “2>&1” copies where the output points at that very moment: the file first — and it holds two lines; the copy first — one
REGULAR EXPRESSIONS
anchors, classes, quantifiers and groups: what a pattern is made of and how it reads, token by token
TIMESTAMPS
date, time and offset from UTC in one string: what it is made of and what it is not
SEMANTIC VERSIONING
what each of the three numbers means, what may follow them, and the order versions stand in
THE CONDITIONS OF TRAP
FIVE conditions from the standard — EXIT and four signals — and three extensions a conformant shell refuses
ARABICA AND ROBUSTA
two species, six varieties, one difference
MATCHA GRADES
ceremonial, premium, culinary — what is behind the words
SPIRIT HOMELANDS
where the law lets Scotch, bourbon, cognac and tequila be made — seven spirits, three scales of place: a country, a part of one, a drawn zone
SPIRIT RAW MATERIALS
what the law lets whisky, rum, brandy and tequila be distilled from — ten spirits, seven raw materials, two regulations
YELLOW TEA
yellowing under a cover · the step no other tea has
FIRST FINGER FOODS
the size, the softness and the shape of a piece for a baby who feeds themselves, by the NHS guidance
THE 9 MAJOR FOOD ALLERGENS
the foods US law singles out by name, and the two ways a label is allowed to say so
CULINARY KNIFE CUTS
julienne, brunoise, bâtonnet and the family of dice — the Culinary Institute of America dimensions, drawn to true scale
NEAPOLITAN PIZZA DOUGH
four ingredients in the proportions written into an EU regulation
POUND CAKE
four equal weights — a recipe whose name is its ratio
PROTEIN IN FOODS
grams per 100 g · animal and plant · and the state each one was weighed in
ENGLISH PUNCTUATION
twelve marks and the three strokes: a name, a job and one working example for each
LANGUAGE FAMILIES
who is related to whom — on the numerals three and two in twenty-seven languages
THE COLLATZ CONJECTURE
halve the even, triple the odd and add one: the road of 27, the record holders and a problem nobody has solved
DIVISIBILITY TESTS
what to read in a written number instead of dividing it: the tail, the digit sum and composite divisors
THE DOOMSDAY RULE
the weekday of any date in the Gregorian calendar, worked out in the head in three steps
NUMBERS 1 TO 100
the hundred chart · primes picked out in colour
LEAP YEARS
one rule, a cycle of four hundred years and the ninety-seven extra days in it
MULTIPLICATION TABLE
1 to 12 · colour intensity = size of the product
THE RULE OF 72
the time it takes steady growth to double: the division you can do in your head, how far it misses and why the divisor is what it is
KINDS OF BASS
eight instruments at one scale · what each is about and how it sounds
CURWEN HAND SIGNS
one hand for each degree of the scale, with the mental effect John Curwen gave it