FRANK'S FACTS

🔢 Number Facts

Numbers don't lie, but they do enjoy startling people. The gap between a million and a billion isn't a step — it's a canyon. A deck of cards holds more possibilities than the atoms under your feet. And humanity spent thousands of years doing arithmetic before anyone agreed that "nothing" deserved its own symbol.

Frank did the math on every entry below — twice, because that's the policy. Calculators down, eyebrows up.

Seconds, Billions & Other Staggering Sums

• FACT #600 A million seconds is about 11 and a half days. Mark that down before reading the next fact.
• FACT #601 A billion seconds is more than 31 years. That's the real distance between a million and a billion: a week and a half versus most of a career.
• FACT #602 A trillion seconds is roughly 31,700 years — reaching back to the Ice Age, long before writing, farming, or the wheel.
• FACT #603 The number of ways to order a 52-card deck is 52 factorial — about 8 followed by 67 zeros. That vastly exceeds the estimated number of atoms in the entire planet Earth.
• FACT #604 The googol — a 1 followed by 100 zeros — was named in the 1930s by nine-year-old Milton Sirotta, nephew of mathematician Edward Kasner, who asked the boy what to call it.
• FACT #605 A googolplex is 10 raised to a googol — a 1 followed by a googol of zeros. You could not write it out in full even using every particle in the observable universe as a zero.
• FACT #606 Until 1974, an official British "billion" meant a million million — what Americans call a trillion. The two countries spent decades disagreeing by a factor of a thousand.
• FACT #607 In the old legend of the chessboard, a sage asks for one grain of rice on the first square, doubled on each square after. The final total, 2⁶⁴ − 1, is 18,446,744,073,709,551,615 grains — more rice than any kingdom has ever grown.
• FACT #608 If you could fold a sheet of paper in half 42 times, the math says the stack would be thicker than the distance from the Earth to the Moon. Doubling is not a polite process.
• FACT #609 In practice, the paper won't cooperate: the record for folding a single sheet in half is 12 folds, set by American student Britney Gallivan in 2002 — using a very, very long sheet.
• FACT #610 Claude Shannon, the father of information theory, estimated the number of possible chess games at around 10¹²⁰ — a figure now known as the Shannon number.
• FACT #611 Graham's number, an upper bound from a genuine math proof, is so large it cannot be written in ordinary notation at all — Guinness World Records once listed it as the largest number ever used in a serious mathematical proof.

Zero: A Biography

• FACT #612 Roman numerals have no zero. The Romans ran an empire, an army, and a tax system without a symbol for nothing.
• FACT #613 The first known rules for treating zero as a number in its own right — adding it, subtracting it, multiplying by it — were written by the Indian mathematician Brahmagupta in 628 AD.
• FACT #614 The word "zero" traces back to the Arabic sifr, meaning "empty" — the same root that gave English the word "cipher."
• FACT #615 There is no year zero in our calendar. The year 1 BC is followed directly by AD 1, which is why pedants (and Frank) note that centuries tick over on years ending in 01.
• FACT #616 Zero is an even number. It sits exactly where an even number should on the number line, divides cleanly by two, and mathematicians consider the matter settled.
• FACT #617 Zero factorial equals one. It sounds like a typo, but 0! = 1 is the definition that makes the rest of mathematics run smoothly — there is exactly one way to arrange nothing.

Prime Real Estate

• FACT #618 Two is the only even prime number. Every other even number has 2 as a divisor, which disqualifies it on the spot.
• FACT #619 One is not a prime number. Mathematicians officially exclude it — partly so that every whole number breaks into primes in exactly one way.
• FACT #620 Euclid proved there are infinitely many primes around 300 BC, and his short, elegant argument is still taught essentially unchanged today.
• FACT #621 The largest known prime, discovered in 2024 by a volunteer in the GIMPS distributed-computing project, is 2^136,279,841 − 1 — a number more than 41 million digits long.
• FACT #622 The Goldbach conjecture — that every even number greater than 2 is the sum of two primes — has been checked by computer into the quintillions and has still never been proven. It has been open since 1742.
• FACT #623 A "perfect" number equals the sum of its smaller divisors: 6 = 1 + 2 + 3. The ancient Greeks knew four of them — 6, 28, 496, and 8,128 — and to this day nobody has found an odd one or proven none exists.
• FACT #624 Some cicadas emerge on 13-year and 17-year cycles — both prime numbers. Many biologists think the prime timing helps them avoid syncing up with predators' population cycles.

Numbers Behaving Strangely

• FACT #625 111,111,111 × 111,111,111 = 12,345,678,987,654,321. The digits march up to nine and back down again. Check it — Frank did.
• FACT #626 Keep adding the digits of any multiple of 9 and you'll eventually reach 9. Take 9 × 487 = 4,383: then 4+3+8+3 = 18, and 1+8 = 9. Every time.
• FACT #627 Take any three-digit number whose first and last digits differ by at least two, reverse it, subtract the smaller from the larger, then add that result to its own reverse. You get 1,089. Always.
• FACT #628 6174 is Kaprekar's constant: take any four-digit number with at least two different digits, arrange its digits largest-to-smallest and smallest-to-largest, subtract, and repeat. Within seven rounds you hit 6174 — and stay there.
• FACT #629 The number 142,857 is cyclic: multiply it by 2, 3, 4, 5, or 6, and you get the same six digits in the same circular order. Multiply it by 7 and it collapses into 999,999.
• FACT #630 0.9999… (repeating forever) is exactly equal to 1. Not close to 1 — equal. Mathematicians can prove it half a dozen ways, and internet commenters have argued about it for as long as there have been internet commenters.
• FACT #631 Some infinities are bigger than others. Georg Cantor proved in the 1870s that the infinity of decimal numbers is strictly larger than the infinity of counting numbers.
• FACT #632 In a room of just 23 people, there's a better-than-even chance that two share a birthday. With 70 people it's above 99.9 percent. This is called the birthday paradox, though the math is not paradoxical — just rude.
• FACT #633 In many real-world data sets — river lengths, populations, street addresses — the leading digit is a 1 about 30 percent of the time. This is Benford's law, and forensic accountants use it to sniff out cooked books.
• FACT #634 Pi has been computed to more than 100 trillion digits — yet NASA's Jet Propulsion Laboratory says about 15 decimal places are plenty to navigate spacecraft across the solar system.
• FACT #635 Pi is irrational — its digits never end and never repeat — a fact proven by Johann Lambert back in 1761.
• FACT #636 2,520 is the smallest number divisible evenly by every number from 1 through 10. The ancients would have called it a very agreeable number; Frank concurs.

Counting in the Wild

• FACT #637 Minus 40 is where the two great temperature scales shake hands: −40° Fahrenheit and −40° Celsius are exactly the same temperature.
• FACT #638 "Forty" is the only number word in English whose letters appear in alphabetical order — and "one" is the only one in reverse alphabetical order.
• FACT #639 Four is the only number in English spelled with exactly as many letters as its value. The lexicon achieves balance precisely once.
• FACT #640 "Eleven" and "twelve" come from Old English roots meaning roughly "one left" and "two left" — as in, left over after counting to ten on your fingers.
• FACT #641 A "score" is twenty — so when Lincoln opened the Gettysburg Address with "Four score and seven years ago," he was saying "87 years ago" with considerably more style.
• FACT #642 A baker's dozen is 13 — traditionally explained by medieval English bread laws, under which selling short weight brought stiff punishment. Bakers tossed in an extra loaf as insurance.
• FACT #643 In much of East Asia the unlucky number is 4, not 13, because its pronunciation in Chinese and Japanese sounds like the word for "death." Some buildings there skip the fourth floor entirely.
• FACT #644 Fear of 13 has its own architecture too: many tall Western buildings simply omit the 13th floor from their elevator panels. The floor exists; the button does not.
• FACT #645 The equals sign was invented in 1557 by Welsh mathematician Robert Recorde, who chose two parallel lines "bicause noe 2 thynges can be moare equalle."
• FACT #646 That same 1557 book contains "zenzizenzizenzic" — an obsolete term for a number's eighth power — which the Oxford English Dictionary notes has more Z's than any other word in its pages.
• FACT #647 Pi Day, March 14 (3/14), happens to be Albert Einstein's birthday — he was born March 14, 1879. The universe occasionally shows off.
• FACT #648 A light-year is a distance, not a time: about 9.5 trillion kilometers, the ground light covers in one year.
• FACT #649 The largest number with a single-word name you'll find in standard dictionaries is the centillion — in American usage, a 1 followed by 303 zeros.

Fifty figures, all of them checked twice — that's the policy. For letters instead of digits, try Word Facts, scramble your timeline with History Facts, or head back to the Library Front Desk »