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  2. Snellen chart - Wikipedia

    en.wikipedia.org/wiki/Snellen_chart

    Snellen chart. Purpose. Snellen chart is used to estimate visual acuity (last three rows are 20/15, 20/13 and 20/10) A Snellen chart is an eye chart that can be used to measure visual acuity. Snellen charts are named after the Dutch ophthalmologist Herman Snellen who developed the chart in 1862 as a measurement tool for the acuity formula ...

  3. Leibniz formula for π - Wikipedia

    en.wikipedia.org/wiki/Leibniz_formula_for_π

    The formula is a special case of the Euler–Boole summation formula for alternating series, providing yet another example of a convergence acceleration technique that can be applied to the Leibniz series. In 1992, Jonathan Borwein and Mark Limber used the first thousand Euler numbers to calculate π to 5,263 decimal places with the Leibniz ...

  4. Golden ratio - Wikipedia

    en.wikipedia.org/wiki/Golden_ratio

    The golden ratio's negative −φ and reciprocal φ−1 are the two roots of the quadratic polynomial x2 + x − 1. The golden ratio is also an algebraic number and even an algebraic integer. It has minimal polynomial. This quadratic polynomial has two roots, and. The golden ratio is also closely related to the polynomial.

  5. Approximations of π - Wikipedia

    en.wikipedia.org/wiki/Approximations_of_π

    In the 3rd century BCE, Archimedes proved the sharp inequalities 223 ⁄ 71 < π < 22 ⁄ 7, by means of regular 96-gons (accuracies of 2·10 −4 and 4·10 −4, respectively). [ 15 ] In the 2nd century CE, Ptolemy used the value 377 ⁄ 120 , the first known approximation accurate to three decimal places (accuracy 2·10 −5 ). [ 16 ]

  6. List of formulae involving π - Wikipedia

    en.wikipedia.org/wiki/List_of_formulae_involving_π

    The buckling formula: A puzzle involving "colliding billiard balls": is the number of collisions made (in ideal conditions, perfectly elastic with no friction) by an object of mass m initially at rest between a fixed wall and another object of mass b2Nm, when struck by the other object. [1] (.

  7. Farey sequence - Wikipedia

    en.wikipedia.org/wiki/Farey_sequence

    In mathematics, the Farey sequence of order n is the sequence of completely reduced fractions, either between 0 and 1, or without this restriction, [a] which when in lowest terms have denominators less than or equal to n, arranged in order of increasing size. With the restricted definition, each Farey sequence starts with the value 0, denoted ...

  8. Visual acuity - Wikipedia

    en.wikipedia.org/wiki/Visual_acuity

    A simple and efficient way to state acuity is by converting the fraction to a decimal: 6/6 then corresponds to an acuity (or a Visus) of 1.0 (see Expression below), while 6/3 corresponds to 2.0, which is often attained by well-corrected healthy young subjects with binocular vision.

  9. Lottery mathematics - Wikipedia

    en.wikipedia.org/wiki/Lottery_mathematics

    In a typical 6/49 game, each player chooses six distinct numbers from a range of 1–49. If the six numbers on a ticket match the numbers drawn by the lottery, the ticket holder is a jackpot winner— regardless of the order of the numbers. The probability of this happening is 1 in 13,983,816. The chance of winning can be demonstrated as ...