Mathematics Stack Exchange
Mathematics Stack Exchange

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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Digit sum of a huge number

I am helping a high school student to solve some challenging problems. I am stuck on the following problem: let $S(n)$ be a digit sum of the integer $n$, e.g. $S(1234)=10$. Find $S(S(S(S(2018^{2018}))))$. I spent some time on this problem but was…
Mikhail Genkin
  • 194
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7 answers

Simplifying a dividing surd?

Can anyone explain how I would simplify this dividing surd: $$\frac{3\sqrt{14}}{\sqrt{42}}$$ As far as I can see $\sqrt{14}$ and $\sqrt{42}$ can't be simplified, right? So how does the division and the multiplication of 3 come into it? Thanks for…
Joey Morani
  • 133
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1 answer

Euler-Vein diagramm

A survey show that $63 \% $ of the Amrican people like cheese whereas $76 \%$ like apples. What can you say about the percentage of the American people that like both cheese and apples? I have worked out on that problem and deduced that the number…
RFZ
  • 16,814
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3 answers

If a salary increase of $7.39\%$ has the value €$4231$, then what is the new salary?

Ryan has been given a salary increase of $7.39\%$. The salary increase is for the value of €$4231$. His salary is now $x$. Solve for $x$. My head is saying $$\begin{align} 4231 / 7.39 &= 572 \\ 572 * 100 &= 57,200 \end{align}$$ is not correct,…
Simon Kiely
  • 123
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1 answer

What's the reason for operator precedence?

What is the underlying concept due to which we prioritize one operator over the other? Is it just a convention?
Chaitanya Baranwal
  • 21
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1 answer

Calculation Error or?

Is it a calculation error or am I missing something? A popular company like Plimus that handles thousands of payments daily can't make this mistake, I thought.
Nimbuz
  • 131
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2 answers

What should I study to fully understand the rules of division between two real numbers

I'm struggling to explain to a child the rules of division, why we add 0's , decimal points, and when we do those things. I know how to do it by memory, but I can't justify those steps. ( I think it is called long division. ) I need to understand…
Victor
  • 87
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What is division?

In mathematics we have the Addition operation from which subtraction and multiplication can be resulted. so it's not wrong to say they both have the concept of addition within them. $$ a*b = a+a+...+a \ \ \ \ \ (b\ times)$$ and $$ a-b = a+ (-b)…
parvin
  • 209
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2 answers

How to root single and double digit non perfect square?

I want to know a simple process to root single or double digit non-perfect square for a competitive exam where time is very limited. For example, $$\sqrt 3$$ $$\sqrt 13$$ You can take any number to show the process.
Rony
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Goldschmidt division example with estimates?

I have found in Gonzalez/Diaz-Herrera/Tucker: Computing Handbook an example for the Goldschmidt division in the case of real numbers. The example is the following: \begin{align} N_0 &= N = 0.625 \\ D_0 &= D = 0.75 \\ F_1 &= 1.3& & &\text{Table…
Lila
  • 479
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7 answers

Extra $100 after borrowing and shopping

I took \$1000 from my friend James and \$500 from Bond. While walking to the shops I lost \$1000 so now I only have \$500. I did some shopping, spending \$300 so now I have \$200 left. I gave \$100 back to James and \$100 back to Bond. Now my…
Nikhil
  • 29
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2 answers

Feynman/Einstein/etc and Basic Maths

Did famous physicists/mathematicians do basic arithmetic (add/sub/div/mult) in their heads, or would they work them out on paper? Is there a scale of difficulty for this? I.e. "Erdos could do 5 digit multiplication in his head, but Feynman could at…
Feindos
  • 23
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Converse of statements and determining if true

quick statement question here: Question The following statements are all true. In each case write out the converse of the statement, and say whether or not the converse is true (give a reason in each case; if it is false, give a counter-example, if…
Polymer
  • 137
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1 answer

providing a set of values to test (x-y)

I've been tasked with providing a comprehensive test for some code that calculates x-y. You can assume that the code is not simply (x-y) My idea is that a good set of values would be: 3 and 7 I think this because they are prime. Can anyone give me…
Lee Brindley
  • 253
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Percentage, Time & work

$A$ is $4$ times as good as $K$ and hence, $K$ takes $50$ more days than $A$ to complete a job. How long will it take to finish the job if they work together? I tried and got: $A=6$%/day $K=1.5$%/day $A+K=7.5$%/day therefore $13.\overline{3}$ days…
Shashi
  • 21
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