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.

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LCM (remainders)

A section of soldiers are rehearsing for the march past for the National Day parade . If they march in Pairs , one soldier will be without a partner . If they march in 3s , 5s, 7s , they will be a soldier short . Calculate the smallest possible…
user307640
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Prove that $2+2\sqrt{12n^2+1}$ is perfect square

Problem: Let $n \in \mathbb{N}$ such that $2+2\sqrt{12n^2+1}$ is the integer. Prove that $2+2\sqrt{12n^2+1}$ is perfect square. I tried to found $n$ such that $\sqrt{12n^2+1}$ is integer, i.e. $12n^2 + 1 = k^2$. It is a Pell equation, and it has…
GAVD
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For some $w$,$x$,$y$,$z$ it holds that $w+x>y+z$. Does that mean that $\sqrt w+\sqrt x> \sqrt y+\sqrt z$ and the other way around?

For some $w$,$x$,$y$,$z$ it holds that $$w+x>y+z. \quad \quad (1)$$Does that mean that $$\sqrt w+\sqrt x> \sqrt y+\sqrt z \quad \quad (2)$$ and the other way around, so if (2) holds then (1) too? Thanks!
Faceb Faceb
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$25$ men are employed to do a work

$25$ men are employed to do a work, which they could finish it in $20$ days but the drop off by $5$ men at the end of every $10$ days. In what time will the work be completed? My Attempt In $20$ days, $25$ men can do $1$ work. In $1$ day, $25$ men…
user335710
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How to maintain equal proportion of investment after buying out a partner

Let's say I have five investors, each owning 20% of a company that is worth $1,000,000. One investor wants to be bought out. So the other investors would, to maintain their equal proportion after the buyout, each pay $50,000 and hence would now have…
JSW189
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Basic arithmetic - trick question.

I have the following question: A baker filled a measuring cup with $3/4$ cup of water. He poured $1/2$ of the water into the batter, and then spilled $1/8$ of the water on the floor. How much water will the baker need to add to what is left in the…
Iván G
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How to find miles per gallon given the following situation?

Fred drives an average of $15,000$ miles per year, and his car gets $20$ miles per gallon of gasoline. The average cost of gasoline is $\$3.25 $ per gallon. He buys a new car. In his new car Fred continues to average $15,000$ miles per year, and…
MATH ASKER
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Scale a range from ($-251$ to $198$) to ($0$ to $100$)?

I have a scoring system set up, where the worst score possible is $-251$, and the best is $198$. How can I scale any results, to fit on a $0$ to $100$ scale? (I.e. if the user gets $-251$, I want to show $0$ instead). I found this thread which got…
BruceWayne
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Is the ten's digit even in any power of 20n+c, where c is an odd digit?

Prove or disprove that in any power of $20n+c$, where $c$ is an odd digit (i.e., $1,3,5,7,9$), the ten's digit is even. This is probably a generalization of this. I tried in the following way. I observe that $(20m+c)(20n+d)$ is $20(20mn+m+n)+cd…
lab bhattacharjee
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Ratios question involving 3 factors

An Alloy A contains copper and tin in a ratio of 3:5 by weight . Another alloy B contains tin and zinc in the ratio of 3:7 by weight . Find the ratio of copper : tin : Zin in a new alloy containing equal weights of alloys A and B . My attempt…
user337744
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Question involving profit and loss

A shopkeeper brought 1840 oranges for 350 dollars . He threw away 52 rotten oranges and packed the rest in boxes of 6 each . He sold these boxes at 1.85 each .calculate the total profit he made if the cost of empty boxes was 4 cents each. My…
user337744
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Clearing concepts for compound interest

A man banked $\$50,000$ into the bank which pays compound interest if $7.6\%$ per annum compounded every 3 months. The formula is $$ A = P \left( 1 + \frac r {100} \right)^n $$ where $P$ is the principal amount, $r$ is the rate of interest…
user307640
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Consecutive consecutive sums of equal value

Given the list of counting numbers, what is the largest amount of consecutive consecutive sums of equal value that can be found? Is there a limit? For example, [1, 2] and [3] are two consecutive consecutive numbers that both add up to 3. (If…
user333696
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Numerical Analysis: Computer Arithmetic

I need to add, multiply fractions (i) Exactly using three-digit decimal arithmetic with chopping (ii) With three-digit arithmetic with rounding Say we had $$\frac{1}{6} + \frac{1}{10}$$ $$\frac{1}{6}=0.16666666$$ Chopping it to three-digit…
cryptomath
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How to Justify the way to solve "A / B * C"

this may be a silly (and duplicated or triplicated) question, but I don't know how justify one or other way to solve this: $A/B*C$ It is clear that: $(A/B)*C \neq A/(B*C)$ One I have heard some people saying that the order of operations…
onlycparra
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