Maths charts
A times table printed as plain black digits is something you read. The same table with colour standing in for the size of the product is something you start to see: the diagonal of squares, the mirror symmetry either side of it, the way the twelve column pulls away from everything else. The arithmetic here is not new — the arrangement is.
Multiplication runs from 1 to 12. The hundred chart picks the primes out in colour, so their uneven scatter becomes visible rather than asserted. Roman numerals set out the subtraction rule and how years are actually written, instead of listing seven symbols and leaving the rest to guesswork.
They belong at a child's eye level: beside a desk, on the back of a bedroom door, in the corner of a classroom. A4 to read up close, A3 when it has to work from across the room.
BARBELL MATHS
the IWF colour code and the plate count: from target weight to each side of the bar, no calculator
BENFORD’S LAW
the first digit of a number: why a one turns up more than six times as often as a nine, and in which sets that is true
THE BIRTHDAY PARADOX
how many people it takes for two of them to share a birthday — and the same count for codes and fingerprints
THE CLOCK FACE
two hands, twelve numbers — how to read the time
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
PASCAL’S TRIANGLE
the first thirteen rows, the sum of each row and the pattern of the odd numbers
REPEATING DECIMALS
which fractions stop, which run for ever, and how to know the length of the repeat without dividing
ROMAN NUMERALS
seven symbols · ones, tens, hundreds · years
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