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Math & Logic · Editorial deck

Numbers with Stories

The numbers with histories, quirks and cultural significance

27 cards~5 minReferences included

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3 chapters · 27 cards
  1. 01
    Patterns, sequences and mathematical constants8 cards · ~1 min
  2. 02
    Scale, powers and mathematical extensions6 cards · ~1 min
  3. 03
    Numbers in culture and stories13 cards · ~2 min

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01
Prompt: This mathematical constant equals a Euclidean circle's circumference divided by its diameter.
Math & LogicA little curiosity
Number · RECALLThis mathematical constant equals a Euclidean circle's circumference divided by its diameter.Think it. Then flip it.
02
Prompt: This constant, written e, is the base of the natural logarithm.
Math & LogicA little curiosity
Number · RECALLThis constant, written e, is the base of the natural logarithm.Think it. Then flip it.
03
Prompt: This ratio equals (1 + √5) / 2 and divides a line so that whole-to-longer equals longer-to-shorter.
Math & LogicA little curiosity
Number · RECALLThis ratio equals (1 + √5) / 2 and divides a line so that whole-to-longer equals longer-to-shorter.Think it. Then flip it.

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The questions inside.

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  1. 01This mathematical constant equals a Euclidean circle's circumference divided by its diameter.RECALL
  2. 02This constant, written e, is the base of the natural logarithm.RECALL
    Euler's Number

    Euler's number, the base of the natural logarithm, appears throughout calculus and compound growth.

    Share this card ↗Source: E (mathematical constant)
  3. 03This ratio equals (1 + √5) / 2 and divides a line so that whole-to-longer equals longer-to-shorter.RECALL
    The Golden Ratio

    The golden ratio, prized for its pleasing proportion, appears in certain natural growth patterns.

    Share this card ↗Source: Golden ratio
  4. 04These integers greater than one have exactly two positive divisors: one and themselves.RECALL
    Prime Numbers

    Prime numbers have exactly two positive divisors: one and themselves. The number one is not prime.

    Share this card ↗Source: Prime number
  5. 05Starting with 0 and 1, each term of this sequence is the sum of the previous two.RECALL
    The Fibonacci Sequence

    The Fibonacci sequence, where each term sums the two before it, shows up in patterns like sunflower spirals.

    Share this card ↗Source: Fibonacci sequence
  6. 06These positive integers equal the sum of their positive divisors excluding themselves; 6 and 28 are examples.RECALL
    Perfect Numbers

    Perfect numbers equal the sum of their positive divisors excluding themselves: 6 = 1 + 2 + 3.

    Share this card ↗Source: Perfect number
  7. 07Each interior entry in this triangular array is the sum of the two entries directly above it.RECALL
    Pascal's Triangle

    Pascal's triangle builds each entry from the sum of the two numbers above it in the row before.

    Share this card ↗Source: Pascal's triangle
  8. 08These numbers read identically forwards and backwards, such as 121 and 1331.RECALL
    Palindromic Numbers

    Palindromic numbers read identically forwards and backwards, a favorite subject of recreational number theory.

    Share this card ↗Source: Palindromic number
  9. 09This mathematical concept represents the unbounded and endless, and is not treated as an ordinary number in arithmetic.RECALL
    Infinity

    Infinity represents the unbounded and endless, and is not treated as an ordinary number in arithmetic.

    Share this card ↗Source: Infinity
  10. 10This number is one followed by a hundred zeros and inspired Google's name.RECALL
    Googol

    A googol, one followed by a hundred zeros, inspired the name of the technology company Google.

    Share this card ↗Source: Googol
  11. 11These numbers are real multiples of i, whose square is −1.RECALL
    Imaginary Numbers

    Imaginary numbers, built from the square root of negative one, prove essential in engineering and quantum physics.

    Share this card ↗Source: Imaginary number
  12. 12Named for Ronald Graham, this famously enormous number arose as an upper bound in a Ramsey-theory problem.RECALL
    Graham's Number

    Graham's number, once the largest number used in a serious proof, is too vast to write in ordinary notation.

    Share this card ↗Source: Graham's number
  13. 13Squaring either of these two values gives the same positive number.IDENTIFY
    Square Roots

    A square root reverses squaring, and every positive number carries both a positive and negative root.

    Share this card ↗Source: Square root
  14. 14These raised numbers indicate powers; positive integer values count repeated factors.RECALL
    Exponents

    Exponents represent repeated multiplication, growing numbers far faster than addition or plain multiplication.

    Share this card ↗Source: Exponentiation
  15. 15This number is the additive identity: adding it leaves any number unchanged.RECALL
    Zero

    Zero developed independently across ancient civilizations, with its placeholder role refined in Indian mathematics.

    Share this card ↗Source: 0
  16. 16This number is the multiplicative identity: multiplying by it leaves any number unchanged.RECALL
    One

    One is the multiplicative identity, leaving any number unchanged whenever it's multiplied by it.

    Share this card ↗Source: 1
  17. 17These numbers lie below zero on the number line.RECALL
    Negative Numbers

    Negative numbers, values less than zero, faced resistance in some early mathematical traditions before wide acceptance.

    Share this card ↗Source: Negative number
  18. 18These expressions represent division with a numerator over a nonzero denominator.RECALL
    Fractions

    Fractions represent a part of a whole using a numerator over a denominator.

    Share this card ↗Source: Fraction
  19. 19This term means per hundred and uses the symbol %.RECALL
    Percent

    Percent, meaning per hundred in Latin, expresses a number as a fraction of one hundred.

    Share this card ↗Source: Percentage
  20. 20Fear of this number is called triskaidekaphobia.RECALL
    The Number 13

    The number 13 is widely deemed unlucky in the West, a fear formally called triskaidekaphobia.

    Share this card ↗Source: 13 (number)
  21. 21This number counts the days of a week and the wonders on the traditional ancient list.RECALL
    The Number 7

    The number 7 recurs as a lucky or significant figure across many of the world's religious and cultural traditions.

    Share this card ↗Source: 7
  22. 22This number is called the number of the beast in the usual reading of Revelation 13:18.RECALL
    The Number 666

    The number 666 is named the number of the beast in the Book of Revelation.

    Share this card ↗Source: 666 (number)
  23. 23This notation writes a nonzero number as a coefficient from 1 up to, but not including, 10 in magnitude, multiplied by a power of ten.RECALL
    Scientific Notation

    Scientific notation writes extreme values compactly as a number multiplied by a power of ten.

    Share this card ↗Source: Scientific notation
  24. 24This numeral system combines letters such as I, V and X.RECALL
    Roman Numerals

    Roman numerals combine letters like I, V, and X, and still appear today on clocks and in movie credits.

    Share this card ↗Source: Roman numerals
  25. 25These base-two numbers use only the digits 0 and 1.RECALL
    Binary Numbers

    Binary numbers use only zero and one, forming the foundational number system used inside computers.

    Share this card ↗Source: Binary number
  26. 26Kilo-, milli- and nano- are examples of these unit modifiers.RECALL
    Metric Prefixes

    Metric prefixes like kilo and nano attach powers of ten to units, letting scientists express extreme quantities concisely.

    Share this card ↗Source: Metric prefix
  27. 27This number answers life, the universe and everything in The Hitchhiker's Guide to the Galaxy.RECALL
    The Number 42

    The number 42 became pop-culture famous as the answer to life, the universe, and everything in The Hitchhiker's Guide to the Galaxy.

    Share this card ↗Source: 42 (number)

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