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8m
comment Calculating average rolling cost stock for bulk products
I don't think you can do that if you want an exact answer. If the last delivery was very expensive, you still have all that fuel in the tank. If the expensive delivery was at the start of last week, you have sold most of it. You are really only keeping track of two numbers at any time-the volume and cost in the tank now. Of course, if prices don't change much you could just use the average price over the last week or month for your cost and not be far wrong.
12m
comment Simplest proof that some number is transcendental?
@MichaelHardy: I see. My first reaction was that the number constructed might be algebraic, but if you posit a list of all the algebraic numbers any number constructed by the Cantor method must be transcendental.
31m
answered Calculating average rolling cost stock for bulk products
37m
comment Simplest proof that some number is transcendental?
Do you mean a proof that some specific number is transcendental or that there is at least one transcendental number? The counting argument of celtschk shows there are uncountably many but does not identify a single one.
2h
comment system of First-Order ODES
Because, for example, $-1.1^n$ does not converge. As long as $|1-h| \lt 1, (1-h)^n$ will converge to zero.
2h
comment cover a given disc with smaller discs
The hexagons are the same solution I proposed, just expressed differently. It will get you close. The problem with small numbers is proving a particular arrangement is optimal is hard. Squares in squares gives a good look at what a mess it is. I don't know if it is NP hard-I think of that in combinatoric problems.
8h
answered cover a given disc with smaller discs
9h
revised Mind-boggling property of a prime
added 134 characters in body
9h
revised if john lends $400 for 9months
edited tags
18h
comment How to calculate the following integral? Can you show me step by step!
A bell should go off in your brain saying $\sin^2 x+\cos^2 x=1$ You can eliminate one trig function this way. Then you might have seen the form.
18h
reviewed Approve How to calculate the following integral? Can you show me step by step!
19h
comment group of functions $\Bbb N \to \Bbb N$
When you say group at the start, it seems you mean set. They are very different and you need to distinguish between them. Do you know the difference?
20h
answered How to solve this 3rd degree polynomial?
1d
answered Mind-boggling property of a prime
1d
revised Quantum Harmonic Oscillators
edited tags
1d
answered Roulette (Probability)
1d
comment I need help with polynomial long division
No, the exponents should decrease by $a$ each step, not by $b$
1d
comment length of period
That is correct. You will have $\max(i,j)$ non-repeating digits, then the repeat will start
1d
comment Solving $x^x \equiv x \pmod{17}$.
I suspect the writer of the original problem did not think so clearly and assumed $x \in [0,16]$. Excellent point. +1
1d
answered prime numbered currency