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  2. Becquerel - Wikipedia

    en.wikipedia.org/wiki/Becquerel

    1 Bq = 1 s −1. A special name was introduced for the reciprocal second (s −1) to represent radioactivity to avoid potentially dangerous mistakes with prefixes.For example, 1 μs −1 would mean 10 6 disintegrations per second: (10 −6 s) −1 = 10 6 s −1, [4] whereas 1 μBq would mean 1 disintegration per 1 million seconds.

  3. Natural logarithm of 2 - Wikipedia

    en.wikipedia.org/wiki/Natural_logarithm_of_2

    In a third layer, the logarithms of rational numbers r = ⁠ a / b ⁠ are computed with ln(r) = ln(a) − ln(b), and logarithms of roots via ln n √ c = ⁠ 1 / n ⁠ ln(c).. The logarithm of 2 is useful in the sense that the powers of 2 are rather densely distributed; finding powers 2 i close to powers b j of other numbers b is comparatively easy, and series representations of ln(b) are ...

  4. Collatz conjecture - Wikipedia

    en.wikipedia.org/wiki/Collatz_conjecture

    Total stopping time is on the x axis, frequency on the y axis. Histogram of total stopping times for the numbers 1 to 10 9. Total stopping time is on the x axis, frequency on the y axis. Iteration time for inputs of 2 to 10 7. Total stopping time of numbers up to 250, 1000, 4000, 20000, 100000, 500000

  5. tf–idf - Wikipedia

    en.wikipedia.org/wiki/Tf–idf

    where f t,d is the raw count of a term in a document, i.e., the number of times that term t occurs in document d. Note the denominator is simply the total number of terms in document d (counting each occurrence of the same term separately). There are various other ways to define term frequency: [5]: 128 the raw count itself: tf(t,d) = f t,d

  6. Specific strength - Wikipedia

    en.wikipedia.org/wiki/Specific_strength

    One Yuri equals 1 Pa⋅m 3 /kg or 1 N⋅m/kg, which is the breaking/yielding force per linear density of the cable under tension. [ 42 ] [ 43 ] A functional Earth space elevator would require a tether of 30–80 megaYuri (corresponding to 3100–8200 km of breaking length).

  7. Abundance of elements in Earth's crust - Wikipedia

    en.wikipedia.org/wiki/Abundance_of_elements_in...

    Abundance (atom fraction) of the chemical elements in Earth's upper continental crust as a function of atomic number; [5] siderophiles shown in yellow Graphs of abundance against atomic number can reveal patterns relating abundance to stellar nucleosynthesis and geochemistry.

  8. Age of the universe - Wikipedia

    en.wikipedia.org/wiki/Age_of_the_universe

    In physical cosmology, the age of the universe is the time elapsed since the Big Bang: 13.8 billion years. [1] Astronomers have two different approaches to determine the age of the universe . One is based on a particle physics model of the early universe called Lambda-CDM , matched to measurements of the distant, and thus old features, like the ...

  9. List of largest exoplanets - Wikipedia

    en.wikipedia.org/wiki/List_of_largest_exoplanets

    The sizes are listed in units of Jupiter radii (R J, 71 492 km).This list is designed to include all planets that are larger than 1.7 times the size of Jupiter.Some well-known planets that are smaller than 1.7 R J (19.055 R 🜨 or 121 536.4 km) have been included for the sake of comparison.