One mark for feet, two for inches

One mark for feet, two for inches — and people argue about why, which is the useful part. Some discussions remember it by syllables: ‘feet’ has one, ‘inch-es’ has two, so the mark count matches. Some people say that is a happy coincidence and not the reason: the marks follow order — the first, larger unit named gets the single mark and the second gets the double, exactly as minutes get one mark and seconds two in time and in angles; individual people trace the marks to Latin words for first and second subdivisions and to the Roman numerals for one and two, and one says the same notation runs through clocks and compasses, which is the thing to hold onto. Many people call the syllable trick flawed or unnecessary against the order rule, and some people defend it — people’s decider is whether the syllable link feels intuitive enough to beat the order rule. Some people warn the syllable version fails for people who say ‘inch’ as one beat, or ‘tomato’ differently in the related trick for feet in a mile — pronunciation is not a stable foundation. Some people point out that others just write 5′10 and let context carry the rest, which one person says is technically wrong and clear from context. One person says the trap is thinking the bigger symbol should mean the bigger unit — it is the other way, and knowing that is the trap is half the fix. One person says the marks are technically primes, not quotation marks or apostrophes, and look the same in many fonts. Some people mix them up or omit one; some people say they have never once confused them and doubt the problem is real. And one line for the reader in a country that measures in centimetres: this question is not yours, and the people who suggested switching systems said so; this page ranks no system and no country.

On your fist or in the rhyme, and people argue about which — so both are rendered below, with their reasons. Many people use the knuckles: make a fist and count the months along it — every knuckle is a thirty-one-day month, every valley a thirty or the twenty-eight; people give the rule, and the order of counting is this page’s own gloss. Many people use the rhyme — thirty days hath September, April, June and November — and say that everything else has thirty-one except February. People argue which method is easier and less error-prone: the knuckle side finds a physical cue on the hand intuitive; the rhyme side prefers a cue made of words and sound. People’s decider is how you remember things — by hand or by ear. Some people add the international line: write the month as a word — 14 Oct 2014 — so that a date read abroad is not the fourteenth month or the tenth day; this page follows that habit.

Yes, with practice, and people disagree about whether you would ever want to. Many people describe counting in binary on the fingers: give each finger a value — thumb one, index two, middle four, ring eight, little finger sixteen — raise the fingers that add to your number, and one hand reaches thirty-one, two hands a thousand and twenty-three. Some people sort out the muddles in the conversation that started it: ordinary finger counting is unary — one finger, one unit — not decimal; the original list of hand shapes ended on the wrong number, because fifteen is every finger but the little one and sixteen is the little finger alone; one person says the powers were assigned backwards against the usual convention; and the system is binary, not decimal, whatever the person who first asked called it. One person says it comes in handy after practice; many people say it is useless, hard to convert back, and no better than a calculator; people also argue whether it is a good tip at all — one person says it is genuinely useful for head-counts, some people say it is handy for high counts and doubling, and some say standard mental counting does the job — and people’s decider is whether you ever need to hold a number above ten in your head without writing it down. The warnings are the practical part: many people say certain shapes look like rude gestures, one says one count resembles a sign some people take as offensive, one says the hand positions might strain the joints over time, and one says it needs some comfort with binary to begin with. Others offer easier variants: a flat hand on a table, pressing the ‘on’ fingers down so you can feel the number; the thumb worth five and the fingers one to four, which reaches ninety-nine with two hands; the palm counted with the five digits, fifteen a hand; an established abacus-like finger system; and sign-language number shapes, which one signer says already reach nine hundred and ninety-nine on one hand. Some people have used binary fingers for years and say they never needed the second hand.

Add the digits, some people say, and the number is divisible by three if the sum is. Two hundred and forty-three: two plus four plus three is nine, nine divides by three, so does two hundred and forty-three. Nine works the same way with nine, one person adds, which is the same rule one step up. It is the one trick here that drew no argument, and the page on this site about finding ten per cent first carries the rest of the arithmetic people do; one person here remembers a conversion factor by memorising the digits and inserting the zero afterwards.

Then drop it, people say, and they say it about their own tricks. Some people warn a mnemonic can be counterproductive when it is harder to remember than the fact it stands for, and others say the phrases here were too silly to help or actively confused them; some people argue the mixed-up marks are not even a common problem, saying the people they know do not confuse them — which some people answer with the experiences above. One person’s alternative to any conversion trick is not to convert: learn your own height in inches as a single number and be done. One person remembers port from starboard because ‘port’ and ‘left’ both have four letters, which is the shape of a good mnemonic — one fact, one hook, no pronunciation. Some people say the plain fix for date confusion is to spell the month, and some people say the plain fix for imperial confusion is to stop using imperial — one person corrects that argument’s favourite statistic, noting that a country often named alongside the US as holding out adopted metric in 2013 — and this page carries that argument in one line and takes no side, because which system you measure in is decided by where you live and not by a tip. A full list of imperial conversions is not covered here; for a picture-based mnemonic that does not depend on language, one person offers the ruler: more ticks to an inch than to a foot.