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
1
vote
0 answers

I "discovered" new arithmetics operators - what are the real names for them and application?

Back in high school I wondered if there is a such a function that has higher growth rate than exponential function. Several years later it came to my mind that this is obvious because we can create arithmetic operators. I'm not a mathematics…
lodzki
  • 21
1
vote
1 answer

Shortcuts for annual percentage change calculations?

Given the number of apples was 2,100,000 3 years ago, is 500,000 this year and has declined at a constant rate during the stated period. Which is the closest estimate of the annual percentage drop between 3 years ago and this year? The choices are:…
Vadym
  • 13
1
vote
1 answer

How do you add and subtract repeating decimals?

I am currently in $8$th grade and I need to know if it’s like normal subtraction or it’s different because the number is infinite. For example: $$. \overline {5} - . \overline {05}$$ Would that equal $.45$ or $.\overline {45}$? I need to know,…
Charlee
  • 11
1
vote
1 answer

First degree problem involving weights

A child has n toys, when we remove the $4$ heaviest toys, the total weight of the toys decreases by $32\%$. Of the rest of the toys, take the $4$ lightest ones, and then the total weight decreases another $\frac{6}{17}$. Therefore, determine the sum…
peta arantes
  • 6,211
1
vote
1 answer

calculate average of second set

let us consider following problem: Set $S$ and Set $T$ both contain x elements. The average of Set S is $40$. If the average of Set $S$ and Set $T$ combined is $50$, which of the following must be true? I. The average of Set T is 60. II. The range…
dato datuashvili
  • 9,194
1
vote
1 answer

Invalid algebraic move in some proofs about impossibility of division by zero

I've come across a certain proof by contradiction at many places, textbooks and online likewise, which seems faulty to me. I'm no mathematician, but I just can't wrap my head around this issue. The story goes like this: Suppose dividing some integer…
Karlo Mikić
  • 37
1
vote
3 answers

Are there positive solutions to $x^q- a = 0$ other than $\sqrt[q]{a}?$

I'm reading a book that says the following (translated): "Before we proceed, let us remember that, given a real number $a > 0$ and a integer $q > 0$, the symbol $\sqrt[q]{a}$ represents a positive real number such that its $q$-power equals to $a$,…
Feripinho
  • 173
1
vote
1 answer

Show that $\forall k,j,m,n \in \mathbb{N}^: 3kn^2 +3jn +3m+2 \notin S=\{x^2 \mid x\in \mathbb{N}\}$

Show that : $$\forall \hspace{2mm} (k,j,m,n) \in \mathbb{N}^4 : 3kn^2 +3jn +3m+2 \notin S=\{x^2 \mid x\in \mathbb{N}\}$$ Clearly this is solvable using modular arithmetic because claiming the expression is a perfect square would yield the…
Adam Boussif
  • 343
  • 1
  • 7
1
vote
1 answer

Mercari says something like, "Your purchase is actually half price". But I don't think so. (Keyword: Shopping)

I am very sorry. I forgot an important condition. This campaign is to give back 50% of the points for the purchase amount for only one order during the period. Mercari is a well-known Japanese company. Currently, Mercari is running a campaign. This…
tchappy ha
  • 8,690
1
vote
4 answers

Is $3 \times 2 = 3+3$ or $2+2+2$?

$3\times 2$ is $3+3$ or $2+2+2$. We know both are correct as multiplication is commutative for whole numbers. But which one is mathematically accurate?
Sann
  • 63
1
vote
1 answer

Motivation of this multiplication method

I have pondered this question for a while while drinking some Chai spice tea (yes the double use of the word "while" makes sense): Suppose $x = 5678$ and $y = 1234$. Now let us label each of the parts of the numbers as follows: $$x =…
geur
  • 33
1
vote
1 answer

Finding $\,\%\,$ of salary relative to another salary

Sam makes $\$65$ per week and Don makes $\$138$ per week. How do I express, as a percentage, how much more Don makes per week than Sam does?
Don P.
  • 113
1
vote
1 answer

Prove that 3S=2Q+P for a geometric progression

I did Arithmetic Progression and Geometric Progression two years ago but this is challenging to me. If 27 is the Pth term,8 is the Qth term and 12 is the Sth term of a G.P,then show that 3S=2Q+P
Dr. NGILAZI BANDA
  • 659
1
vote
3 answers

Question on Faulty clock

Clock A loses 4 minutes every hour, clock B always shows the correct time and clock C gains 3 minutes every hour. On a Monday, all the three clocks showed the same time, 8 PM. On the following Wednesday, when the clock C shows 2 PM, what time will…
S.S
  • 1,207
1
vote
1 answer

How to construct an integer weighted average with integer weights?

In order to write a test case for a program, I want to calculate the weighted average based on weights $w_i$ and values $X_i$. Weighted average $W$ is given as $$ W = \frac{\sum_{i=1}^n w_i*X_i}{\sum_{i=1}^n w_i} $$ I need three distinct weights,…
TMOTTM
  • 177
1 2 3
…
99 100