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In the most familiar acuity test, a Snellen chart is placed at a standard distance: 6 metres. At this distance, the symbols on the line representing "normal" acuity subtend an angle of five minutes of arc, and the thickness of the lines and of the spaces between the lines subtends one minute of arc. This line, designated 6/6 (or 20/20), is the ...
Homeopathic dilutions. In homeopathy, homeopathic dilution (known by practitioners as "dynamisation" or "potentisation") is a process in which a substance is diluted with alcohol or distilled water and then vigorously shaken in a process called "succussion". Insoluble solids, such as quartz and oyster shell, are diluted by grinding them with ...
For 6/6 = 1.0 acuity, the size of a letter on the Snellen chart or Landolt C chart is a visual angle of 5 arc minutes (1 arc min = 1/60 of a degree), which is a 43 point font at 20 feet. [10] By the design of a typical optotype (like a Snellen E or a Landolt C), the critical gap that needs to be resolved is 1/5 this value, i.e., 1 arc min.
The decimal expansion of the golden ratio [1] has been calculated to an accuracy of ten trillion (=) digits. [ 66 ] In the complex plane , the fifth roots of unity z = e 2 π k i / 5 {\displaystyle z=e^{2\pi ki/5}} (for an integer k {\textstyle k} ) satisfying z 5 = 1 {\displaystyle z^{5}=1} are the vertices of a pentagon.
A simple fraction (also known as a common fraction or vulgar fraction, where vulgar is Latin for "common") is a rational number written as a / b or , where a and b are both integers. [ 9] As with other fractions, the denominator ( b) cannot be zero. Examples include 1 2 , − 8 5 , −8 5 , and 8 −5 .
Perfect number. In number theory, a perfect number is a positive integer that is equal to the sum of its positive proper divisors, that is, divisors excluding the number itself. For instance, 6 has proper divisors 1, 2 and 3, and 1 + 2 + 3 = 6, so 6 is a perfect number. The next perfect number is 28, since 1 + 2 + 4 + 7 + 14 = 28.
Snellen chart. The Snellen chart, which dates back to 1862, is also commonly used to estimate visual acuity.A Snellen score of 6/6 (20/20), indicating that an observer can resolve details as small as 1 minute of visual angle, corresponds to a LogMAR of 0 (since the base-10 logarithm of 1 is 0); a Snellen score of 6/12 (20/40), indicating an observer can resolve details as small as 2 minutes of ...
In number theory, the partition function p(n) represents the number of possible partitions of a non-negative integer n. For instance, p(4) = 5 because the integer 4 has the five partitions 1 + 1 + 1 + 1, 1 + 1 + 2, 1 + 3, 2 + 2, and 4 . No closed-form expression for the partition function is known, but it has both asymptotic expansions that ...