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