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# Search for maths in Topics

My friend asked me this one, I couldn't figure it out but I think the question itself is somehow flawed.Anyway, so here it goes: A kid has to buy a toy of 100 Rupees, he takes Rs.50 from his father and 50 from his mother. Later when he goes to the store he finds that the toy is only 97 rupees, he buys the toy and 3 rupees are left, still with me? Now he goes to his mother and father and out of those 3 rupees gives one rupee to his father, one rupee to his mother and keeps the remaining 1 rupee aside (not for himself). Now here is the question, as he has already given 1 rupee to his mother and father each, he has remaining 49 rupees to pay each one, so, my friend asks that add 49 to 49, 98, and then add to it the remaining 1 rupee he had kept aside, 99. Where did the remaining 1 rupee go? I just can't understand what is he trying to ask, the calculation he just did, I think, has nothing to do with amount the kid has to pay or paid.

Question by the-science-dude    |  last reply

### Math Problem

I need a formula to answer a question such as this: If a 7 feet 300 lb man can have 24 beers before becoming intoxicated, how many beers can a 5 feet 100 lb man consume before becoming intoxicated. Or direct me to a site where I might have this answered. Thanks in advance.

Topic by Sovereignty    |  last reply

### Math question

I need help on this question, it come sup often in one form or another in mathcounts, so I need to know how to solve it There are 5 letters, 3 of each, take out 10. AAA, BBB, CCC, DDD, EEE. You do not replace letters after taking one out, and order does matter. How many ways to arrange the letters are there?

Topic by starwing123    |  last reply

What will be the equation for y for the following graph? y=5, x=0 y=4, x=1 y=3, x=2 y=2, x=3 y=1, x=4 y=0, x=5

Question by Wisaam    |  last reply

This is one of those crazy things put up on Facebook. From what i can tell most people are getting this wrong. But you follow the rules for simple math -- Rule 1:   First perform any calculations inside parentheses. Rule 2:   Next perform all multiplications and divisions, working from left to right. Rule 3:   Lastly, perform all additions and subtractions, working from left to right. So it is       3-18+2= -13    And yet people think I am wrong ??   I simplified it even more for them ---- 3+2 =5     5-18= -13  Why are so many getting this wrong?  Or maybe I am wrong---- time to go back to grade school I guess.

Question by Vyger    |  last reply

### math fromula

Thought this would be an appropriate place to share some of what i thought was interesting information to do with the area of a triangle and how numbers co-relate. To round off a square to 100cm square, one quarter of that area is 25cm square, (10cmx10cm =100/(div)25%=25cm), the area of a  right angle triangle with sides measuring ~7.0710cm,  equals ~25% of 100cm square,  25cm square of area,  (7.0710/2=3.5355 x7.0710=24.9995205). 7.5937 if it is an equilateral triangle. it is a standard size i use,  a handy measurement if you use templates for construction because it in  some way represents a metric increment, thanks, Kim (the formula i used is half the base times the height,  unless im mistaken i recall that is the correct formula?  though i am not a full time mathamatician.  for the equalateral triangle i used a web based polygon area calculator.)

Topic by QSDR    |  last reply

### A math challenge...

Ok, so there's this coding language called FCML- a simple language built for a scripting engine in a game (Fantastic Contraption). I'm wanting to write a script that implements the graph of an equation in the form of axn+b to that gaming language. To clarify, this is to create a "level", or a series of bricks, and fitting them along the line of a user-specified equation. The coding language is very simple:StaticRect (x1, y1), (x2, y2), zWhere x1 and y1 are coordinates on a Cartesian coordinate plane, x2 and y2 are lengths and widths of the rectangle, respectively, and z is the rotation of the brick. The brick is positioned with respect to it's center; i.e. it's center is positioned with x1 and y1. It's mathematically possible; it's just very confusing for a 7th grader. With a little calculus, trigonometry, and algebra I've come up with these formulas, and would just like to see what others come up with before implementing them.Input: y=axn90-tan-1(1/naxn-1) for z10 for y2root((axn-a(x-.5)n) + .25) for x2axn+.5(axn-a(x-.5)n) for y1x - .25 for x1I'm aiming for an accuracy of 1/2.

### Alice in Wonderland & maths?

In New Scientist No2739/40/41 (Christmas 2009) is an article by Melaine Bayley (DPhil Oxford) in which she explains how Lewis Carroll (Charles Dogson) is taking a stab at the new mathematics of the time in his famous work. For example, the Mad Hatter's Tea Party is related to Hamilton's maths. Interesing stuff (to me anyway...) Read here

Topic by lemonie    |  last reply

### Math / word question

If I had a million dollars and spent one thousand dollars a day,how many years would it take to spend the million dollars?

Question by suer69    |  last reply

### Determining Distance With Math? Answered

Ok, I am only a freshman in high-school so I have know idea how to determine how high an object will travel at a given weight and size.  Does anybody know what this math is called and were I can learn it.

Question by jj.inc    |  last reply

### LED Math Help

I want to create a LED grow light but i am having trouble with the math. I have 5 blue LEDs that are 3w( Vf: 3-3.4 v and If:700ma). Now i want to wire these in a series. So if i were to use two of these for example, would it require more volts and the same current. So: 2@3v = 6v @700ma.

Question by Lord_Tryndamere    |  last reply

### math/school help

I need some help in school. today, we had an exam. our teacher did a very bad job explaining the subject matter, and i could barley hear her over everyone talking. the manual i have for math did not explain anything either. anyhow, i probably didnt do too well on the exam.what should i tell my parents? they have a hard time believing that the teacher is at fault too. any help?

Topic by tech-king    |  last reply

### Calculator Programs for Math

I've been working on some programs for my calculator recently and have decided to share them. I made these myself from scratch. If you want to modify go ahead just credit me. Don't sell them. And don't use them in math class if your teacher says not to. The programs are a follows: a quadratic formula solver, parabola solver, slope of a linear equation finder, and y-intercept finder. The programs work on TI-83's and TI-84's. If you have questions on how to use them or how to put them on your calculator please leave a comment!

Topic by sardines454    |  last reply

### Oscillator Trouble/Math ?

I have a "step-up" transformer from a DVD player that I really want to experiment with, but I know I need some form of alternating current to use it. I just finished taking a 3-week summer camp at which I learned about electronics, and there I encountered the 555 circuit. It's simple to build; I can just connect all the pieces on a small breadboard, considering I have several 555 chips. But what makes me a little miffed is that anything over 6V could burn out the chip's components. So I gave up on the 555 oscillator, and turned to the simple(-er) LC circuit. I want to have around 60 Hz to simulate the mains frequency, but I have no idea what capacitance or inductance I should use. Furthermore, I don't quite understand how to achieve a specific inductance based on coil turns, coil diameter, coil length, etc. If anybody could clear me up on these concepts, I'd greatly appreciate it.

Question by Umniscient

### Do we need math?

So, do we need math? As if you didn't know my question from the title...

### Math wiki formatting on instructables

Alright Instructables, I fold. It is with a sense of shame that I must ask: Does Instructables have a method (be a clandestine feature or a workaround) to allow a user to enter formatted math text (ex. summation signs, integrals, greek letters even)? In particular, I was trying to get latex to work (I thought I had seen another user do so once) on the wiki, but thus far my efforts have proved fruitless. Anyone out there know a way to do this?

Topic by purduecer    |  last reply

### Integrating Math into My Programs?

First off, let me just say I love numbers.  Absolutely love them.  Unfortunately, I don't particularly have the know-how (possibly ingenuity) to integrate it into my programming beyond a few variables for text-based games.  Do you know of any good ways to do this for say, gravity simulations and such?  Links are always welcome. Thank you!

Question by StarscreamClone    |  last reply

### BAATCH code - Math Problem?

Heey! I wanna make a .BAT program that'll help me do homework. I'm lazy to type the same formula to calculator, so I wanna make a program with preset formula. I wanna make the program solve this formula: S=3,14*r2 and O=3,14*d - Surface and Circuit of a cirle (I'm not english, my english's not the best). I wanna make the program solve these formulas. When you type r=3, it will say CIRCUIT IS (r*2 and then 3,14*'the r*2') AND SURFACE IS (3,14*r2 - the 2 should be in upper right corner) When you type d=3, it will say CIRCUIT IS (3,14*d) and SIZE IS (d:2 and then 3,14*'d:2 answer'2 - again, 2 in upper right corner. Please.......

Question by NicoFilippo    |  last reply

### "Knex War?" (The Math Bit)

Topic by Sharir1701    |  last reply

### solar cell

Please i dwell in Nigeria which hardware device can i get copper sheet

Question by yomite    |  last reply

### A SIMPLE instruction guide on statistics and chemistry?

Statistics and chemistry equations are some of the most complex calculations for people who did not grow up in a science background but are essential for students looking to further their degrees in fields that require bio chemistry while students excel in practicals its the calculations that cause problems like log, ph calculations, various option in statistics when to use which rule. A better tutorial for college level statistics and from basic chemistry to college level would be appreciated by various students the world over. Thank you in advance all areas of these two fields would be appreciated.

Question by Rainmakker84    |  last reply

### a word of caution

Don't drink and derive

Topic by corey_caffeine    |  last reply

### Did you learn trigonometry rules off by heart at school and how did you manage to survive it?

I'm having a bit of a formula overflow at the moment... Actually, the idea of learning 32 of them and reciting in class sounds a bit 19-century to me. I was even more disappointed when I opened an English Maths textbook and didn't see any signs of such terrifying practice. Did anyone here learn it, and how did you manage to survive??? PS The worst part is that we have to be able to recognise them pronounced and pronounce them, and not only be able to write them...

Question by gruffalo child    |  last reply

### Mathematical formulae and wind instrument help.? Answered

Is there a mathematical formula for the arrangement of hole on a flute or better a recorder. In addition has anyone every tried to make a saxophone mouthpiece   ? I am interested in trying to make a DIY version of a Xaphoon http://www.youtube.com/watch?v=j3Wnx2VYZq8

Question by rickharris    |  last reply

### I guess you call this homework? Answered

BUT It isn't my home work. A friend Emailed me this and asked if I knew how to work it out. Th answer was no - do any one help - No teaching involved here my friend is in his 70's. A car engine has four camshafts each supported by three journal bearings. The engine runs at a maximum of 8000rpm, and the camshafts rotate at half engine speed. Assuming the engine oil to be 40 degrees - Determine the maximum power absorbed by the camshaft bearings. Other data given below journal bearing = 35 mm bearing axial length = 20 mm radial clearance = 0.018 mm oil grade = vg32 oil density = 890kg m   ̅³̇

Question by rickharris    |  last reply

### Why "Vortex" for Vortex math and devices?

Topic by Downunder35m

### Ancient technologies revisited - Ancient math

Topic by Downunder35m    |  last reply

### How can I add a math formula (created with a math editor) in the text of an Instructable?

I just want to include some formulas in my text, I've tried to edit it with a math editor, save it as a pic and paste  it in the text but in the preview disappears.Thanks Massimo

Question by MassimoF11    |  last reply

### volume of water from a litre of hydrogen? Answered

Im no chemist but I am interested in what volume in litres of water would be produced from 1 litre of liquid hydrogen if burnt in air. Of course it would evaperate and be disspersed but would be 8 litres?  2h2 + O2 = 2h2O I believe the chemical formular

Question by lrdforster    |  last reply

### Math Teacher and his Tech-savvy Pranks

I know it's a little late for the April Fool's Day prank contest, but this guy would take the cake: www.urlesque.com/2010/04/06/math-teacher-pranks/ Enjoy, and please PLEASE post if you attempt anything of this epic scale!

Topic by erosser

### I got my math quiz back...

Yes I know I have horrible handwriting... But I think 1000% on a quiz cancels that out. I actuallt got a 50/50 but im not complaining...

Topic by astrozombies138    |  last reply

### A Third Math Sign - not just positive or negative

I was thinking about a random thing the other week. We have positive and negative signs in widespread and ubiquitous use in mathematics. What if we had a third sign? The number line would look like the one in the picture. It's not even a line anymore. Since I am absolutely dumbfounded as to how even the basic operations would play out in this type of system (although I have a rough idea for addition and subtraction), and nor do I know what the possible applications for a redundant sign could be, I'm just putting this here. Got ideas? Fire away.

Topic by nutsandbolts_64    |  last reply

### Does anyone want a really enjoyable Maths problem I've been thinking about for days?

Here is it: Prove that (Xn): (any) n Xn=1+1/1!+1/2!+1/3!.....+1/n! converges and lim(Xn)=lim(Yn), where                     n Yn=(1+1/n) ( (any) is upside down A, n in the end is power) I know asking homework-based questions is unethical, but I've been doing it for 2 weeks and my teacher tells me it is very enjoyable... Any ideas?

Question by gruffalo child    |  last reply

### How do I calculate buoyancy? Answered

How do I do it?  Floating on water (please include examples) btw - I'm making a boat out of a motorbike

Question by SirNoodlehe    |  last reply

### Arduino as a programming project?

I decided to make something with Arduino as a school programming project, because it would be nice to learn something more complex than playing with LED arrays. The question is WHAT? It has to be a PROGRAMMING project, not an electronics one and therefore must be interesting and hard to do. Everything I can think of is a lot of electronics with some 50 lines of code at the end... Any ideas?

Question by gruffalo child    |  last reply

### Any Maple alternatives?

I need a something that plots graphs (three-dimensional is better), solves differential equations and counts integrals - Maple would be ideal - plus I think that learning to use it is a nice constructive thing to do in the summer before starting university, but it costs a lot more than I can painlessly pay...  Any ideas? Probably some older versions are free or cheap, or there are any other programs? I looks like I'm only going to use it in the summer as they probably should give something to students... To be more specific, I'm trying to learn GTR and calculate some geodesics.

Question by gruffalo child    |  last reply

### how to make a foldable for a order of operations math lesson?

I need to come up with activities and foldables for a math lesson and the subject is order of operations

Question by karynlucero    |  last reply

### what are some math problems to make a efficient circuit? Answered

I am trying to make my own wind mill using a stepper motor, capacitor,led, and a resister. My problem is that my dad wants me to make it more efficient meaning making the led go brighter and longer. I curently have 11 capacitors in parallel ,one resister. what are some math equations i can use to find out how to make this more efficient and how do i use the problems?

Question by lookwhatjoeysmaking    |  last reply

### Math formula(e) needed: tesseract model construction?

Although I CAN do this without the math formula(e) to figure it all out, I would like to have it for a quicker method of figuring out size, etc. so I didn't have to use up so much material in guessing. I would like to construct the tesseract I have pictured here, using rigid clear plastic sheets or panels.   Given a said size for the "inner cube" say 2 inches (approx. 5 cm or about 51 mm) what formula(e) must I use to calculate the panels' dimensions to connect to the larger cube (knowing full well this will depend on the size of the larger cube....say approx. 4 inches across (about 10 cm or 102 mm)? The reason I'd like the formula(e) is that I may need to increase the size of the center cube by an inch or so, and this would allow me to do so without having to go through the "trial and error" thing so many times. I would, of course, want the center cube to be "centered", if possible or shall I say as close as possible. Thanks....

Topic by Goodhart    |  last reply

### Math help needed for converting volts/watts in solar

Here's what I know: Watts (P) = Amps (I) x Volts (E). What I don't know is if I have a solar panel that is rated at 12v, 0.125 mW I can do the above equation to get that my amps are 0.01. Does that sound right? My real Q, is what is the best power battery to store this energy? Should I only use 8 "D" cells? Could I use a 12 v motorcycle battery? If I use Ni-Cd batteries, is the fact that the batteries are rated at 2500 ma make any difference? Is there a website where I can get a good feel for what batteries are good for what type of activity, solar cells, etc? thanx, sam

Topic by wanzie    |  last reply

### Need a maths geek to answer a question about boiling water.

Hi all. I'm finally starting the prototype of my solar condenser this week, though this question doesn't relate to it directly, but to using it to power a steam distiller to purify water. How much water will ten kilowatt hours boil? ie, if I have one kilowatt of solar energy coming in over ten hours and 100% of it goes into heating the water. Also, for extra credit, assume the water is in a black plastic container also in the sun, so the water is preheated to whatever temperature that would be likely to heat it to. cheers!

Topic by SolarFlower_org    |  last reply

### Why do i solve the sum in this way (mathematics)?

The sum is as given below: "There are two cars A and B.They start from the same point at the same time and travel in a circular path .Car A can complete one round in 18 minutes whereas car B can complete the round in 16 minutes. After how much time will they meet?"   my maths teacher told me to take the LCM(least common multiple) of their respective completion times of a round. Can anybody please explain to me as to why i should take the LCM. Also i would be greatful  if you could explain it simply.Cheerio.

Question by Strontium    |  last reply

### Can you use a Speak and Spell cartridge on a Speak and Math? Answered

I bought a Speak and Spell on Ebay for circuit bending, but alas, I fried it. It came with an expansion cartridgl. I want to pursue this circuit bending project, so (going off another schematic), I bought a Speak and Math off of Ebay. What would happen if I put the Speak and Spell cartridge in the Speak and Math?

Question by noahh    |  last reply

I'm trying to figure out the best way to wire up 187 LEDs on a panel. They will probably be 3.4~3.8V, I'n not sure how the math works to determine what kind of power I'll need or what the best way to wire them would be. Help would be greatly appreciated. Thanks in advance!

Topic by aintMichael    |  last reply

### How to solve multiple maths operation using Digital roots

Hello all, I have a question. (560 / 32 )x (720 / 48 )= ? a) 262.5 b) 255 c)  263.5 d) 271.25 Is there any way to get correct answer using any shortcut or digital roots? I want to do it fast Thanks

Topic by abharti    |  last reply

### Simple LED question... if you know how to do the math!

A few years ago, I found a plastic pumpkin with a "faux flame" set up inside of it. I liked the idea of it and am trying to replicate it to make a few faux flame torches around my backyard for halloween this year. The idea is that there is a small 12v fan near the top of a tube. There two or three leds glued around the top of the tube. The fan blows a flame shaped piece of fabric up and the leds light it up to look like fire. (possible future instructable?) Unfortunately, I don't know much about circuits and the math of electricity. I found a small fan (12vdc .13a) and 2 red leds (2.6v). I hooked them up in parallel with a 12v 1amp wall wort coverter but nothing happens. I have done a little reading online and wonder about needing a resistor in front of the leds. I wanted to hook it up in parallel to get the fan to work at full speed to make the fabric really blow. From all the circuits I have seen online, this one seems really simple, if I knew what I was doing. Can anyone draw me up a simple diagram? What am I goofing up on here? Thanks! Matt

Topic by mckeephoto    |  last reply

### How to concatenate two or more linear interpolants? Answered

I have a graph, it is not a straight line but a random curve, I want to do linear interpolation of different data set points. I read it here: http://en.wikipedia.org/wiki/Linear_interpolation#Interpolation_of_a_data_set And it says that: "Linear interpolation on a set of data points (x0, y0), (x1, y1), ..., (xn, yn) is defined as the concatenation of linear interpolants between each pair of data points." So. how can I concatenate two or more linear interpolants? And can you please also give an example of it?

Question by Wisaam    |  last reply

### Is there any website where i can get math puzzles to solve? Answered

Me and my friend llove to solve math puzzles...but we r currently in dearth of problems! Any help?

Question by Yashknowsbetter    |  last reply

### How can I put symbols or math formulas in the answer box? Answered

I was trying to answer a question earlier and wanted to put in the formula for figuring the surface area of a sphere.  Short of adding an image, I couldn't figure out how, so I just wrote out the formula. Is there a way to insert math symbols in the answer box?

Question by Burf    |  last reply