Here they are.

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# Day: July 11, 2019

# the 3d Pythagorean Theorem

(It’s just a double application of the 2d Pythagorean Theorem, but it’s worth noting explicitly.)

Here’s the scoop.

keywords: Mathematics, Geometry, diagonal, rectangular prism

# lorem ipsum

Placeholders are the demigods of logistics.

keywords: utility, savings

# points of intersection

Finding points of intersection undergirds much of mathematical work.

keywords: Mathematics, pattern, big picture, observation

# How many 2-digit positive integers are there such that the product of their digits is 24?

Here’s the scoop.

keywords: Mathematics, Number Theory, easy problem

# easy problem about a 2-digit positive integer

If a two-digit positive integer has its digits reversed, the resulting integer differs from the original by 27. By how much do the two digits differ?

Here’s the scoop.

keywords: Mathematics, Number Theory

# the 2-digit positive integers problem

Each of x, y, and z is a 2-digit positive integer (in base ten), and:

1) 4x + y – 19z = 0

2) 2x + y – 14z = 0

Solve for x.

This problem (stated in terms of a, b, and c, and with base ten merely presumed), is on the web, among a set of tournament problems.

Here is the set of tournament problems (as a pdf file).

keywords: Mathematics, Number Theory, challenge