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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High school problem with the fractions on exams

I have this problem with the fraction: Sylvia is among 12 students to have successfully taken successfully taken the challenging General Mathematics exam at the university. To pass it, in fact, it was necessary to succeed in both the first test and…
Sebastiano
  • 7,649
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1 answer

How do I know what ratio I need to invert in an inverse compound rule of three problem?

Example: Alejandro's father hired 15 workers who, working 40 days for 10 hours a day, built a swimming pool in his house with a capacity for 80,000 liters of water; If Alejandro hires 10 of these workers to work 6 hours a day and build another pool…
Alejandra
  • 25
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1 answer

the least number that is when successively divided by 7,5,3 leaves successive reminders 4,4,1 respectively is

Options 172,144,102,109 my answer is this the correct way to find the least number ?
unknown
  • 37
2
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3 answers

Profit sharing among investors

Abigail, Bart, and Cathy invested \$2,400, \$3,600, and \$6,000 respectively to start a partnership business. At the end of the first year, the business earned a profit of 40% on the initial investment. The profit was taxed at the rate of 30%. The…
Katheryne Sparrow
  • 21
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5 answers

Why is 33 1/3% of 240 = 79.992 wrong?

I'm embarrassed to ask this fundamental question among questions of particle filters but : my daughter just had this marked wrong on a test. The teacher said the answer was 1/3 of 240 = 80. On one level I understand this using fractions (80 *…
amoricai
  • 21
2
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1 answer

Am I allowed to add and subtract expressions whose domain might not be $ \mathbb{R} $

We all know the trick of adding and subtracting an expression, for example to calculate: $ \int \frac{2x}{2x + 1} \, dx = \int \frac{2x + 1 - 1}{2x + 1} \, dx = \int \frac{2x + 1}{2x + 1} \, dx + \int \frac{1}{2x + 1} \, dx = \int 1 \, dx + \int…
talopl
  • 999
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2 answers

How do I solve $(68!+68^{86} ) \mathrm{ \ mod \ }75$?

I feel like it's really easy and i'm just misunderstanding something. It's obvious that I need to use Wilson' and Fermat's theorems: $(p-1)!≡-1\mathrm{ \ mod \ }p$ $a^{p-1}≡1\mathrm{ \ mod \ }p$ if $p$ does not divide $a$. i figured i might divide…
mnogoetashka
  • 31
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2 answers

Name for addition and multiplication of a sequence of digits, using varying order of mathematical symbols, with the same outcome

I am looking for the correct name for mathematics like this: $$ 1 + 2 \times 3 + 4 \times 5 + 6 \times 7 + 8 = 77 $$ $$ 1 + 2 + 3 + 4 + 5 + 6 + 7 \times 8 = 77 $$ $$ 1 \times 2 \times 3 + 4 + 5 + 6 + 7 \times 8 = 77 $$ That is to say: maths that…
Potherca
  • 23
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2 answers

How to compute $\frac{63.5\times 0.5\times 10\times 60}{2\times 96500}$ without a calculator?

Thankfully, I have been provided 4 options: (a) $0.0987$ (b) $0.0897$ (c) $0.0798$ (d) $0.0789$ My attempt $$\begin{aligned} \frac{63.5\times 0.5\times 10\times 60}{2\times 96500} &= \frac{63.5\times 0.5\times 600}{2\times 96500} \\ &= \frac{63.5…
tryingtobeastoic
  • 3,176
2
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1 answer

What is the most reasonable method to round equidistant numbers?

At school we were taught that (+/-)0.5 goes to nearest "higher" number or "round half away from zero". That is 0.5 -> 1 and -0.5 -> -1. While that looks nice and all (five goes to ten regardless of a sign), the more you think about it, the less it…
Qwerty
  • 121
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1 answer

Methods of solving for unknown variables based on sum and difference

Question: $$\begin{align} &\text{Joe has a sailboat.}&\\ &\text{His sailboat is twice as old as Joe was when his sailboat was as old as Joe is now.}&\\ &\text{Their age's combined is 56 years.}&\\ \end{align}$$ Here's my go at it, It's basically…
JohnWO
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4 answers

How to Calculate the Disk Space Required to Store Googolplex?

Given the googolplex number and that 1 gigabyte = 1 073 741 824 bytes. How would I calculate the amount of disk space required to store the googolplex number?
GateKiller
  • 129
2
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1 answer

truncate, ceiling, floor, and...?

Truncation rounds negative numbers upwards, and positive numbers downwards. Floor rounds all numbers downwards, and ceiling rounds all numbers upwards. Is there a term/notation/whatever for the fourth operation, which rounds negative numbers…
Sneftel
  • 760
2
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1 answer

Find $x\in\mathbb Z$ to $x-4\mid x\sqrt{x}-2x$

Find $x\in\mathbb Z$ to $x-4\mid x\sqrt{x}-2x$. This is my idea: Because $x\in\mathbb Z \Rightarrow x-4\in\mathbb Z$, so $x\sqrt{x}-2x\in\mathbb Z\Rightarrow x\sqrt{x}+2x\in\mathbb Z$ So to $x\in\mathbb Z$ to\begin{gather*}x-4\mid…
AndonisRyder
  • 439
2
votes
1 answer

solve gcd $n^3+3n^2-5$ and $n+2$ with bezout

Hello I have to solve $\gcd (n^3+3n^2-5 , n+2)$ with bezout Here’s how I did it: bezout says $a$ and $b$ are co prime if and only if $au+bv = 1$. Then I did : $(n+2)(n^2+n-2) -(n^3+3n^2-5)$ I found one so their $\gcd$ is equal to $1$. Did I get the…
achla95
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