Mathematics

Area-Bisecting Lines

Every line going through the center of a square bisects its area. Does every line going through the center of an equilateral triangle bisect its area too?

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Chord-bisecting Chords

A circle of radius 5 has chord AB with length 6.  A second chord is drawn here and is bisected by AB.

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Friendly Factor Pairs

The number 6 has two pairs of factors: 2x3 and 1x6.  These two pairs of factors are called friendly because the sum of one pair is equal to the difference of the other pair, ie. 2+3 = 6-1 = 5.

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Sierpinski Pyramid

Let’s remove the central portion of a regular tetrahedron such that what remains are 4 tetrahedrons each with half of the side length of the original.

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Digit Sum Divisors

Consider a natural number N and the sum of its digits S.  Let’s call a divisor of S a Digit Sum Divisor of N.

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Beads in a Bracelet

We have a bracelet made of yellow and green beads, and we want to divide each coloured beads evenly among friends with the least number of cuts.

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Finding Paths

In this 4x4 grid, if we choose two squares, for which pairs of squares can we find a path from one square to the other, moving only vertically or horizontally at each step, and visiting every square in the grid exactly once?

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Crossing Numbers

From the list of numbers 1 to n, cross out every other number starting with the smallest and repeat the process with the remaining numbers until only one number is left.  What number would that be for a given n?

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Probability Thoughts

If the possible fairness of a coin is a continuum, the probability of the coin being exactly fair (50H/50T) is 0.  To begin exploring, let’s say the coin can only be rigged heads (100H/0T), fair (50H/50T), or rigged tails (0H/100T).

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