1119 posts tagged with math.
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Pennies from Heaven
I have what I believe is a two gallon jar of mixed loose change. At my bank I can pay a flat fee of $6 for them to count it, vs using their CoinStar style machine for a 2.5% fee. (I don't want to cash out for gift cards at the grocery store). What is the likely best deal?
Help with math for a DIY project
I am tiling a rectangular table. I want to make an inner rectangle of 4x4 tiles and an outer rectangle of different sized tiles, but what should the dimensions be of that inner rectangle? What size/number of tiles should I use for the outer rectangle? [more inside]
Set me free with LibreTexts.
I've stumbled across LibreTexts.Math, and it could be useful to me, but I don't see how to access it in an organized way. How would I go about getting it to appear like a regular eBook?
One used car for another
After seeking advice on getting my daughter a car, I think my smartest move is to trade in my paid off 2017 Tahoe for a smaller used vehicle that my daughter can use. What's the best way to negotiate a used-to-used car swap and not get completely fleeced? [more inside]
Iregular rules - tiling patterns
I'd like to know how I can calculate the minimum sawn edge for a repeat tiling pattern using an irregular repeat polygon of the Cairo type [ArXic 200Kb .pdf]. Assuming this is solveable I want to repeat it for different-shaped spaces. [more inside]
Best math apps/games for middle schooler
My bright almost-8th-grader is struggling with math basics, and I know that a big part of it is that back in 3rd/4th grade, they stopped drilling the multiplication table as part of the general curriculum. So that fundamental knowledge is missing for a lot of kids :( More under the fold... [more inside]
Self taught programer math catchup tutorials?
I'm self teaching Arduino programing and I quit math as soon as possible in high school and that's finally catching up with me. Easy / best way to learn the math I need? [more inside]
Gifts for the Calculating Grad
My kid is graduating at the end of the month, and will be studying statistics at university.
It has been suggested to me that a really high end calculator would be a good graduation gift and useful in their secondary education.
1) is this true? (they did not need one in HS)
2) If so, what would be the Cadillac of handheld calculators for a stats kid?
What exactly does professional bookkeeping do for a small non-profit?
As a non-accounting person, I'm vaguely aware that accounting can be complicated. Since starting in my ED role about two months ago, though, I'm not sure that our operation is complicated enough to warrant what we spend for a large external accounting firm. This is not related to auditing, which is done separately.
Many more details about our specific circumstances inside. [more inside]
What kind of real estate/math person/professional do I need?
I'm an empty-nester-retiree contemplating different configurations of home ownership in the next 18 months. Is there some professional role that can do the math to give me data to help with the decision? [more inside]
math this math
I need help building an efficient (1 step) excel formula to do a very specific piece of math. Please and thank you! [more inside]
Not the Kelvin universe I'm used to
I have an Elgato ring light that has an API that uses a weird number for the color temperature. What is it?? [more inside]
Optimize my experimental setup
My experimental setup is analog to the following (no people involved):
I have 8 groups of 4 subjects and their weight. There are 4 treatments, so in the end each treatment has 2 groups with 8 subjects. I want the variation in weight between the groups and the variation inside the group to be minimal. For this scenario I brute forced it, there are 2520 possible permutations (8!/2!^4) and I calculated ANOVA for all of them and picked the one with the highest p value. I did this in R on my work PC and it took about 3 minutes.
It would be possible two split each group in half, and then I could optimize the group composition. However, there are too many possibilities to brute force it. I can distribute the 4 individuals in each group in three ways: aabb abab abba. Then I have 3^8=6561 possibilities to combine these groups. Now I have 16 groups for my four treatments, but to get all of the combinations is too much for my PC, there are 16!/4!^4=63063000 of them for every one of my 6561 possible split scenarios.
How would I go about finding the perfect group split for my experiment?
DEI Math - what is it good for beyond platitudes and slogans?
I am hoping that someone can explain the meaning and rationale for "DEI math". I am particularly interested in the high school level since many years ago I taught math at a private H.S.
Slide from the 44th annual meeting of the North American chapter of the international group for the psychology of mathematics education: " When are we going to admit that many best practices in mathematics education create toxic spaces for historically marginalized students and are violent toward them?” [more inside]
ScienceMathFilter: Please help me identify these equations of motion...
I was give a snapshot of a whiteboard with a series of equations that am trying to identify. The writing is illegible in a number of places, but some of it I can make out. It is obviously some sort of equations of motion involving the gravitational acceleration on some mass m, versus another force Fw, and some velocities - here are a few things I can make out:
ma = mg - Fw
v(t) = vT*(1 - e^(-b*A*t/m)) [more inside]
How to maximize my chances of passing?
Does anyone have any tips or tricks for making the most out of my study time and/or keeping myself in the right headspace for exams for a must-pass class? [more inside]
Launch trajectories for launches from Florida
Is there a good source for launch trajectories for launches from Florida? [more inside]
For the mathematically inclined: help identify a power series
While playing around with some math stuff related to finding (complex) roots of polynomial functions, this funky little power series-like thing popped out and I'm not sure I know what it is. [more inside]
How high to see all of Illinois?
Is there a place (building) in Illinois high enough that you could see the entire state on a clear day? How do I figure it out? My friend is from the Rockies and now lives in Illinois and if it's doable it might be a fun day trip when I visit. [more inside]
Looking for good math stuff to show my son over the summer
My son has a really good head for math. He's been taking high school math as an eighth grader. I'm looking for good math stuff to keep his brain stimulated over the summer. I'm looking for stuff they don't shovel at you in school. I want weird stuff that will really push him. [more inside]
Good math-based, sports-related investigations for middle schoolers?
I'm looking for some sports-related ways to approach math for kids (middle school to early high school). Ideally, looking for high-concept approaches (e.g. "How can knowing about math help me to win at sports?") that could become long-form projects/investigations rather than short one-off activities.
I have a ridiculous alphabetical / mathematical question
Three words: CHEF CHELSEA CHERRY (P.S. I'm not shouting) ...Alphabetically, which word is CHELSEA closer to: CHEF or CHERRY? And, more importantly* why? Can you help me come up with a mathematical model for this?
*this is not important at all. [more inside]
Looking for an app to help my son with first grade math
My son is struggle with math. He’s in first grade and they are currently covering word problems and basic addition involving regrouping and subtraction with two and three digit numbers. Are there any iOS apps that can help him with this? [more inside]
A book about matrices and linear transformations written for children
The book may not (or may) have been published. It may only exist as photocopies and pdfs, but it is not a figment of my imagination. It may have covered other subjects like solving equations, but I only flipped through the first few pages before losing track of it.
I'm looking for some leads on finding it. [more inside]
Card trick question: difficulty level -- different language, math
When I was a child, my grandfather showed me a card trick, based on a mnemonic in a language other than English. I would like to reproduce it in English. [more inside]
Help with Excel formula: percent increase to 'x times as much'
I need to write an Excel formula that converts percentages to an 'x times as much' figure. It is breaking my brain. [more inside]
Math concept books for neurodivergent children?
What are your recommendations for resources, books, graphs, charts, etc for teaching math concepts to neurodivergent learners? Assume we're looking for three age ranges: 4-6, 7-9, 10+. Thanks!
What's wrong with this clique math?
I was watching this video about P = NP problems and it described the clique problem. I had a thought about one way to solve the clique problem - though of course with very little math knowledge I'm very aware that I have not Solved Math and likely am overlooking something major (the Wiki article went past my head). What's the matter with my possible algorithm? [more inside]
Explain credit cards in YNAB to me like I'm 5
I signed up for a year of YNAB after reading the book from my library. It makes sense to me! I can follow it! I can even reconcile it against my bank accounts! ... Except for my freaking credit card debt.
Goal: Pay back anything that I spend on the cards as well as my minimum payment and/or interest. But the math will not math for me like the rest of the program does. Every time I think I have it I realize that I don't and I've broken something. [more inside]
Wartime UK postcard: Schoolboy cryptography? Maths homework? Help!
I recently bought WW1 postcards (Twitter thread) from a market stall here in London. As you'll see from the link, I have reason to believe they're from a British boarding school pupil writing to an older member of his family back home in Yorkshire. It's the first image in the second tweet there that intrigues me. Is this a family code of some kind? A form of mathematical notation I'm not familiar with? Let's solve this, Metafilter!
Calculus instructor's editions and solutions manuals?
Help me find an older calculus textbook with solutions to all the problems. [more inside]
count the chickens hypothetical
Right now there are lots of chickens in lots of egg-laying factories. How many chickens would fit in the same amount of space if they all were 100% ethically raised? [more inside]
The Mathematician and the Cat
In the last year I read about a mathematician or scientist who wanted to credit his cat for helping him with much of his work. I believe he lived in the 19th century. Publishers refused, but eventually, after his death, a statue was erected of him and his cat together. [more inside]
How many possible paths?
I am trying to calculate the number of unique paths through a grid that loop back to only one starting point.
I think of this as an extension of the old telephone game. If I tell one person, and they tell the next person, what are all the possible paths for the message to travel through the group and return to me? [more inside]
How do people ever pay off interest-bearing debt??
My cash stuffing rabbithole (see here) led me to the world of debt snowballs and debt avalanches. People's demonstration of the math never seems to take accruing interest into account - when I try to model this for myself, it seems the debt just keeps getting higher and higher both ways. But clearly both methods have worked for people. What am I missing? [more inside]
Modern math theory for little kids
My kid is 6 and really enjoys math. Her teachers have already given her a solid understanding of basic multiplication, division and algebra. But we haven't done much at home, and I'm wondering how to support her interest. I'd like to educate myself a bit first. Could you recommend things I can read/watch to better understand doing math with kids? My own skills are solid (technical career) but I don't know much about teaching! [more inside]
What's after numberblocks
My 5 year old son learned math from NumberBlocks. Like in two weeks over last winter break, he went from knowing how to count to adding, subtracting, multiplying, dividing, squaring, cubing, negative numbers. etc. etc. In Montessori he built up this skills He LOVES numberblocks. But he's definitely ready to add new math concepts like exponents (which he's already doing) and fractions and more thinking about negative numbers. And I'm ready to not hear the NumberBlocks theme ever again. Is there a show like numberblocks (in that it really gets at understanding concepts) for more advanced math? Not interested in apps or ads. [more inside]
Square One TV for today's fourth-grader
I loved Square One TV, the math show for elementary schoolers, sooo much when I was 9. But part of what I liked was that it made math seem sort of adult and hip to me, with references to MTV and pop culture. My kid would find all the cultural references completely baffling; I barely understood them in 1994. What kind of content exists to make recreational math seem at least a little cool that way for today's kid? [more inside]
What's this math/statistics word I'm looking for?
I want to say that one analysis is ____ of another. Or that two analyses are _______. Where the blank word means -- "look, they're the same thing in a different form. They're just simple transformations of each other. You can pull out your calculator and turn this one into that one. They spit out different numbers but they mean EXACTLY the same thing" I feel like there's a word for this. [more inside]
Math: Probability and combinatronics
Ok... so I'm looking at a candidate for a job position and I notice on his resume the following:
Between his mobile number and my mobile number (10 digit, US format) there are 9 numbers in common, 5 of which are in the right position. [more inside]
I'd like to know where to find copies of old math exams from 100+ years
I'd like to know where to find copies of old math exams from 100+ years ago. [more inside]
Survey Design - should I stop a census with survey response-level
I'm a little farther away from survey design than I used to be, but I'm seeing a massive swing on a survey delivered on a regular cadence (not just at delivery) and I vaguely remember a reason why and it had to do with the way the initial population is identified. [more inside]
What's a good book or resource to learn math from scratch (for adult)?
As a young child I was never taught real math... that is I was never taught how to solve a problem. It was all memorization. [more inside]
Basic permutation calculation - brain is broken so is Google
I can't believe I can't do this simple calculation. I also can't believe I can't even word the question properly to get a relevant answer from Google.
Four teams play each other once. No ties are possible. What is the number of possible outcomes. [more inside]
What are the odds?
MegaMillions is up to ~$830 million, the fourth highest jackpot in US history. I know the odds that I will win are vanishingly small, but what are the odds that someone will win?
Recommendations for math tuition for Grades 4-6
My kid is struggling with maths and needs individual tuition. She hates in-person classes and is very reluctant to ask at school. She's now in an online group tuition that is torture getting her to complete the worksheets and then sit through a 1.5 hour class at a fixed time.
She doesn't like gamification or Khan Academy videos (we'll try again if that's the best currently). I'll pay for good online maths that's no frills, explains concepts clearly, and allows lots of practice so she can do sprints at her own pace.
How should I learn Linear Algebra?
I'm a mathematically-minded person, but informally; I was great with math in high school and so-so in college, didn't deal well with calculus, love recreational mathematics on my own terms, and do best when I have a good conceptual basis for any bit of mathematical theory. (I do great with planar geometry. I do okaaay with symbolic algebra.) But I never learned linear algebra and matrices, despite them applying to a *lot* of things I'm otherwise interested in. Where's a good, accessible, concept-driven way to get familiar with lin alg territory?
Are there more true statements or false statements?
My 11yo son asked me this at bedtime. Are there more true statements, or false statements?
At first I assumed that there were more false statements, because while there's only one correct answer for, say, 1+1=?, there are infinite wrong answers. But then we realized that if you change = to ≠ then it evens out. Is this answerable?
Sample Testing in an Incomplete Block Design
I cannot even begin how to work this conundrum, please help me with a testing plan for sample distribution with a minimum of participants. [more inside]
Perplexed by pixels
Is it fair to say that a resolution of 1280 x 1024 has twice as many pixels as a resolution 640 x 512?