How many positive integers are factors of a given number?
I've been trying to find / generate a formula for the following problem: Given a number, how many positive integers are factors of this number. In pr...
Bright entertainment trends with youth appeal.
I've been trying to find / generate a formula for the following problem: Given a number, how many positive integers are factors of this number. In pr...
In permutations and combinations, what is the concept behind this derangement formula? $$D_n = n!\left(1-\dfrac{1}{1!}+\dfrac{1}{2!}-\dfrac{1}{3!}+...+(-1...
$\newcommand{\Cov}{\operatorname{Cov}}$As an extension of this question (covariance of normal distribution), I'd like to give a specific example, and...
Sorry I'm a bit confuse, are you allow to use Pythagoras in a non right angled triangle?
Wikipedia in Italian has a sketch-of-proof that Robinson arithmetic is not complete, since commutativity of addition is undecidable. The sketch of proof c...
I am computing the Hessian of a scalar field, and tried using numdifftools. This seems to work, but was quite slow so I wrote my own approach using finite...
I'm having trouble understanding in a mathematical sense the reason why: (1) $$Null(A) = [R(A^{T})]^\perp $$ (2) $$Null(A^T) = [R(A)]^\perp$$ What I&...
What is 72,000 km/hour in Système Relativistique (SR) units? I am getting 1/14490 or 1/14490th of the speed of light.
While going through an equation today i realized that sum of first (n-1) numbers is [n*(n-1)/2] which is equal to combinations of two items out of n i.e [...
A toy company would like to estimate the proportions of toys produced by their younger workers. In a random sample of 300 toys, they found that 75 were de...