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Questions tagged [arithmetic]

Questions on basic arithmetic involving numerical quantities only. Questions involving variable values (other than the result of the operation) should be placed under the (algebra-precalculus) tag. Questions about number theory (sometimes called "arithmetic") should not use this tag and should instead use (number-theory) or (elementary-number-theory).

Arithmetic is defined as operations upon numbers using $4$ main operations along with many others:

addition - the sum of two numbers

subtraction - the difference of two numbers also defined as the addition of negative numbers

multiplication - the area of a rectangle with sides of lengths equal to the two operands

division - the number of times one number can be subtracted from another before equaling zero. Sometimes it will allow decimals and in other cases there will be a remainder left over when a number doesn't go into another evenly

See Arithmetic.

6283 questions
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What is $(-1)^{\frac{1}{7}} + (-1)^{\frac{3}{7}} + (-1)^{\frac{5}{7}} + (-1)^{\frac{9}{7}} + (-1)^{\frac{11}{7}}+ (-1)^{\frac{13}{7}}$?

The question is as given in the title. According to WolframAlpha, the answer is 1, but I am curious as to how one gets that. I tried simplifying the above into $$6(-1)^{\frac{1}{7}}$$ however that does not give 1.
AstroInt
  • 333
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Percentage + abstract/substract question

My calculation was (5520*5845)*31% and I got value 10,001,964. Closest answer is 10,100,000. Is the answer right? Thanks
Alvin
  • 39
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Mohan can do a piece of work in ....

Mohan can do a piece of work in 10 days and Sohan can do it in 12 days. They do the work in alternate days. If Sohan starts the work in the first day, in how many days will the work be completed? My Attempt: In $10$ days, Mohan can do $1$ work. In…
pi-π
  • 7,416
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Find the time taken to travel between two cities

At a speed of 40 Kmph-1 , vehicle takes 6 hours to travel the distance between two cities. Find the total number of hours it takes to travel the distance between two cities if one half of the distance is traveled at a speed of 30 kmph-1 and the…
user360471
  • 493
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Calculate GCD(Fib(531185354674),Fib(613570636967))

I picked this problem from here http://mathalon.in/?page=show_problem.php&pid=106 . I don't know how to solve it accurately. The number seems too to be done by any computation method.
Hemant Verma
  • 63
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A simple depreciation problem

Question 2: The share price of a public company fell 4% on each day of a week, from Monday to Friday. What is the price of a share at the end of the trading day on Friday, if the share was valued at $20 on the Sunday of the same week? I could do…
sonam
  • 251
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How does 5.9-7.66=-1.76?

Sorry for such an easy question but this has been confusing me like crazy. I have borrowed like normal and subtracted like every other problem, and the answer I get is -2.24. How is this wrong?
user351535
  • 75
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Subtraction non-associativity when presented as addition

It's well known that the action of subtraction isn't associative: $(7-4)-1 \neq 7-(4-1)$ However, subtraction is simply the addition of negative numbers... so the inequality above can be presented as: $(7+(-4))+(-1) \neq 7+(-1)\cdot(4+(-1))$ So,…
unlimitednzt
  • 147
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Bizarre question given to student at learning center

I work at a learning center and this problem came up during a lesson. The student stared at it for a while, and after looking at it myself, I am also puzzled. An average of 368 students attend each of Jinlow Elementary School's home soccer games. …
Jonathan Hebert
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Prove that $108^3-7^3$ is a multiple of $101$

Encountered the next problem: prove that $108^3-7^3$ is the multiple to $101$. As I understand if $c$ is the multiple to $a$ it means that there exist $b\in\mathbb{N}$ that $ab=c$. So i want to factor out $101$ from the expression, and I don't see…
Mr Bubble Hubble
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How to find the number of x per second given the time elapsed?

I'm benchmarking a websocket server and I am very poor at math so please forgive me. I am recording the amount of messages sent, and the elapsed time: Players Connected: 2. Messages Sent: 3528, Elapsed Time: 180.7 seconds I am wondering if it's…
MakeWebSocketsGreatAgain
  • 23
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Unsolved arithmetic exercise for printing numbers in book

Here is the exercise from the "Arithmetic" book (ISBN: 5-02-013764-2). There are 1989 numbers had printed to enumerate book's pages. How many pages in book? Honestly I decided to refresh my arithmetic knowledge at all but stuck with that…
Крайст
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arithmetic problem concerning equilateral triangle

An equilateral triangle exists with vertices $(0,0), (a,11)$ and $(b,37)$. Using the distance formula three times, I eventually arrive to: $$a^2 + 121 = b^2 + 1369 = a^2 + b^2 - 2ab + 676$$ The only problem is that since none of the equations are…
user201254
  • 51
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What is the logic of priority of operations?

For example $2+2\times2$ is $6$ not $8$. Actually $+$ and $\times$ are binary operations on $\mathbb Z$. but here there is an triple $(2,2,2)$ which we sent to $2+2\times 2$. So we have to put and order for applying operations as binary such that…
student forever
  • 1,266
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How do I average two numbers that are already averaged?

$50$ juniors and seniors are tested. $35$ of them average $80%$. $15$ of them average $70%$. What is the average of the class of $50$? We tried $(70+80)/2$ but that was $75$ and the real answer is $78$ but we don't know how to get…
Heather
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