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Kaprekar Number
The \( 6174 \) Phenomenon For any \( 4 \)-digit number where not all the places have the same number, repeat the calculation of subtracting the smallest number from the largest number that can be obtained by rearranging the numbers in each place, and you will always arrive at \( 6174 \) at the end.…
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Algebra is also called a Ring
Algebra and Its Meanings The Japanese translation of “algebra” is “代数,” which typically evokes the concept of “algebra (代数学)” in the context of mathematics, such as basic algebraic equations and operations. However, the term “algebra” has a broader and more specialized meaning within higher mathematics and abstract algebra. In this other sense, “algebra” is translated…
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The Area of a Circle is Zero?
We are familiar with the formula for the area of a circle with radius \(r \), centered at a certain point, which is given by \( \pi r^2 \). However, this can be misleading. The reason is that the definition of a circle is “the set of points equidistant from a given point⭕️.” In other…
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Hex
One of my favorite board games is Hex🔶🔷. The rules are incredibly simple. Hex is a two-player game played on a rhombus-shaped board covered with hexagonal tiles. The standard board is an \( 11 \times 11 \) grid with \( 121 \) hexagons, though Hex can be played on boards of any size. Hex was…
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Brouwer’s Fixed-Point Theorem
Here, I’ll discuss a famous fixed-point theorem from topology. Definition and Statement of the Theorem A fixed point is literally a point that moves to itself when moved by a continuous mapping. Formally, let \( X \) be a topological space, and \( f:X→X \) a continuous map. A point \( x \) that satisfies…