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  2. Persistence of a number - Wikipedia

    en.wikipedia.org/wiki/Persistence_of_a_number

    The additive persistence of 2718 is 2: first we find that 2 + 7 + 1 + 8 = 18, and then that 1 + 8 = 9. The multiplicative persistence of 39 is 3, because it takes three steps to reduce 39 to a single digit: 39 → 27 → 14 → 4. Also, 39 is the smallest number of multiplicative persistence 3.

  3. Multiplicative digital root - Wikipedia

    en.wikipedia.org/wiki/Multiplicative_digital_root

    Based on these restrictions, the number of candidates for -digit numbers with record-breaking persistence is only proportional to the square of , a tiny fraction of all possible -digit numbers. However, any number that is missing from the sequence above would have multiplicative persistence > 11; such numbers are believed not to exist, and ...

  4. Digital root - Wikipedia

    en.wikipedia.org/wiki/Digital_root

    The next number in the sequence (the smallest number of additive persistence 5) is 2 × 10 2×(10 22 − 1)/9 − 1 (that is, 1 followed by 2 222 222 222 222 222 222 222 nines). For any fixed base, the sum of the digits of a number is proportional to its logarithm ; therefore, the additive persistence is proportional to the iterated logarithm .

  5. Persistence - Wikipedia

    en.wikipedia.org/wiki/Persistence

    Image persistence, in LCD monitors; Persistence (computer science), the characteristic of data that outlives the execution of the program that created it; Persistence of a number, a mathematical quality of numbers; Persistent data structure, a data structure that always preserves the previous version of itself when it is modified

  6. Topological data analysis - Wikipedia

    en.wikipedia.org/wiki/Topological_data_analysis

    The circle-valued map might be useful, "persistence theory for circle-valued maps promises to play the role for some vector fields as does the standard persistence theory for scalar fields", as commented in Dan Burghelea et al. [58] The main difference is that Jordan cells (very similar in format to the Jordan blocks in linear algebra) are ...

  7. List of mathematical constants - Wikipedia

    en.wikipedia.org/wiki/List_of_mathematical_constants

    A mathematical constant is a key number whose value is fixed by an unambiguous definition, often referred to by a symbol (e.g., an alphabet letter), or by mathematicians' names to facilitate using it across multiple mathematical problems. [1]

  8. Digit sum - Wikipedia

    en.wikipedia.org/wiki/Digit_sum

    Digit sums and digital roots can be used for quick divisibility tests: a natural number is divisible by 3 or 9 if and only if its digit sum (or digital root) is divisible by 3 or 9, respectively. For divisibility by 9, this test is called the rule of nines and is the basis of the casting out nines technique for checking calculations.

  9. Investigations in Numbers, Data, and Space - Wikipedia

    en.wikipedia.org/wiki/Investigations_in_Numbers...

    Investigations was developed between 1990 and 1998. It was just one of a number of reform mathematics curricula initially funded by a National Science Foundation grant. The goals of the project raised opposition to the curriculum from critics (both parents and mathematics teachers) who objected to the emphasis on conceptual learning instead of instruction in more recognized specific methods ...