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I've always been interested in quick mental math/arithmetic. e.g. Sometimes I find myself checking a bill by adding it up the way we were taught in school. I'm sure there are better ways. What are the best books/resources? Looking for math techniques that can be used often, are easy to remember and easy to use!
posted by storybored on Nov 12, 2020 - 9 answers

I want to be less clumsy with numbers / be more fluid with maths - are there any games / websites / drills that could help with that? [more inside]
posted by Crookshanks_Meow on Jan 19, 2018 - 6 answers

Sometime within the last two years, I read a positive review of a mathematics book for children of at least kindergarten age that introduced math concepts using the number line as a conceptual focus. I'd appreciate any help in trying to identify this book. [more inside]
posted by Svejk on Jul 5, 2016 - 3 answers

This isn't getting in the way of anything practical, but it's niggling that I don't understand the technicalities. [more inside]
posted by protorp on Feb 29, 2016 - 7 answers

In three cells in a single column in Microsoft Excel, I'd like to be able to input a number in the bottom cell, have the middle cell calculate what a 6% sales tax on the figure below it is, and provide the amount before that 6% tax in the top cell. Any help will be appreciated. The last math class I took was 44 years ago and I didn't pay much attention in that one.
posted by imjustsaying on May 8, 2015 - 8 answers

I'm trying to do some online landscape planning but don't have all the information I need. I have problems with simple math. Can y'all help me out? [more inside]
posted by patheral on Apr 19, 2015 - 9 answers

Why do we have order of operations rules in arithmetic instead of just strictly evaluating expressions from left to right (possibly with parenthesis for grouping if we really wanted to change the order)?
posted by Reverend John on Mar 11, 2014 - 9 answers

What are some of the newest methods being used these days to teach young children arithmetic? [more inside]
posted by Dansaman on Feb 10, 2014 - 3 answers

I'm taking a standardized test on Wednesday with the Government of Canada and they ask individuals four types of questions. The type that I struggle with are the arithmetic problems... specifically determining the formulas to solve word problems. I was hoping someone might be able to point me in the direction of a website or easily accessible textbook to practice today and tomorrow before the test. [more inside]
posted by DorothySmith on Jul 15, 2013 - 11 answers

We want to assess a list of vendors in two domains: Accessibility and Cost. We have two tools that we are using to essentially score them in each of these domains separately. The Accessibility assessment tool totals 110 points; the Cost tool totals 90 points. We want a final score for each vendor that combines the domains and is out of 100. We want the Accessibility score to "count" about 20% more than the Cost score in the final because it is more important to us. How do we do this? [more inside]
posted by OmieWise on Mar 14, 2013 - 10 answers

Harmonic or Arithmetic Mean?: I'm trying to settle an argument with my wife - is using the arithmetic mean or harmonic mean more appropriate when finding the "average" number of, say, online comments made by a large number of people, where a significant portion of them make only one comment and a few people make the bulk of the comments? [more inside]
posted by salsamander on Jun 2, 2012 - 13 answers

Help me to learn math as an adult when I still despise the frustrating beast from my childhood! [more inside]
posted by DisreputableDog on Mar 24, 2012 - 20 answers

Basically, what it says. I've been brushing up on my math skills via Khan Academy, and I'm running into a problem I hit when I was in school. Basically, the math *concepts*, like Algebra, Trig, and the like? I'm able to get really easily. But, manipulating the numbers and doing the basic arithmetic? Hard. Sometimes even with a calculator, I'll miss carrying over a negative sign, and I'll get the problem wrong, despite knowing the concepts really, really well. What's going on here? Is my ADHD not under control? Are these symptoms of Dyscalculia? What? Ideas, hivemind! [more inside]
posted by spinifex23 on Mar 10, 2012 - 28 answers

HELP. My daughter hates math, and I'm not helping -- in fact, I think I'm making it worse!! How do I help my girl with her math homework in a way that makes math fun and interesting!? I feel like I'm at a moment pivotal to her future, and I'm BLOWING it!! [more inside]
posted by Alaska Jack on Feb 10, 2012 - 38 answers

What is the difference between floating point accuracy and precision?
posted by conrad101 on Jan 2, 2012 - 10 answers

I've seen people compute complex arithmetic off the top of their head. How do they do it? [more inside]
posted by Christ, what an asshole on Apr 30, 2009 - 13 answers

Is there an online or otherwise calculator utility that can produce a multiplication column to the nearest integer if I need to (and I do need to) multiply a given integer (specifically, 8.57143) by all the integers from 1 to about 600, displayed in a list so that I don't have to multiply it each time? I may need to do other 600-deep columns with other decimally numbers, a few at most. I need to see the result, better yet print it. [more inside]
posted by gorgor_balabala on Jul 10, 2008 - 17 answers

Faster techniques for grabbing lines of a file and doing text manipulation and arithmetic via shell (or other) scripting? [more inside]
posted by Blazecock Pileon on May 9, 2008 - 20 answers

ABC x D = BADC. What single numbers (1-9) do the letters represent? Is there any way to arrive at the answer (a) by logical deduction all the way rather than with some trial-and-error and (b) so that a 10-year-old can follow the logic? [more inside]
posted by londongeezer on Sep 16, 2007 - 14 answers