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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Making $r$ the subject of a formula

Making r the subject $ S = 2xr^2 + xrl $ On the right side of the equation , I factorise $r$- $ r ( 2xr + xl ) $ I realised that I still have a $r$ inside $2xr$ . How do I remove that $r$ ? Thanks for the help !
user307640
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Convert currency base from one base to another

Consider a list of currency rates where the base is USD: 1 USD = 0.90390 EUR 0.74771 GBP 1.30101 CAD how can I convert the base from USD to GBP, such that I end up with: 1 GBP = 1.33767 USD 1.20993 EUR 1.74146 CAD What kind of formula do I…
user
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combining 3 ratio together with no equal volumes

An Alloy A contains copper and tin in the ratio of 3 : 5 by weight. Another Alloy B contains tin and zinc in the ratio 3:7 by weight . Find the ratio of copper : tin : zinc in a new alloy containing equal weights of alloys A And B They are not…
user307640
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What amount can be paid at the end of every month in perpetuity from an endowment of $350,000 which is earning 5.4% compounded monthly?

What amount can be paid at the end of every month in perpetuity from an endowment of $350,000 which is earning 5.4% compounded monthly? Am trying to apply the compound interest formula but it isn't working
Ben
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Finding the min/max of consecutive numbers which equal a given sum

Given a consecutive list of numbers of size $n$, and a total sum figure $t$, what is the simplest way of finding the minimum $min$ and maximum $max$ numbers of that consecutive list? For example, $t = 10$ $n = 4$ $1 + 2 + 3 + 4 = 10$ $min = 1, max…
Carl
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A,B and C can do a piece of

A can do a piece of work in $10$ days, B in $20$ days and C in $30$ days. If A is assisted by B and C turn by turn in alternate days, in how many days the work might have been completed? My Attempt: In $1$ day, A can do $\frac {1}{10}$ work. In $1$…
xxyy aazz
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First digit of a very long number

Suppose I have a set of numbers eg:{1,8,9,6,5,10} I want to keep a track of the first digit of the number obtained by multiplying the above numbers. 1*8*9*6*5*10 the answer is 21600 ,the first digit of which is 2. Now my question is how do I keep a…
user345973
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Figuring out the percentage of A in relation to B

I have two numbers 13.49 and 7.8 I want to know how to figure out how much 7.8 is of 13.49 in percentage e.g. 7.8 is 80% of 13.49 What is the best way to do this?
mk_89
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Is any simple formula to find impact of new value addition on total

Sorry for my poor math skills. Please down vote after stating the reason. I have 4 values A, B, C and D. Following is the calculation. $(A + B + C) - D = Total.$ Later any of $A,B,C$ or $D$ will replace with new value. Eg: $A = 100$ $B = 200$ $C…
Praveen Vijayan
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Converting imperial-based equations to metric

I have the following equation: $\frac{n\times2.2046}2\times0.0284130625$ to: convert kg to lbs, divide by $2$, then convert the result from oz to L is there a shortcut to do this without the conversion to imperial? yeah, I know this is probably a…
bee.catt
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Why is $-3^4 = -81$ and $(-3)^4 = 81$?

How do you express $-3^4$ to get an answer of $-81$. And how is $(-3)^4$ expressed to get the answer of $81$?
daz
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Why diferent calculators give different values for same expression?

So I was working with this expression: $1111 = 5 * 2^t$ after working it out until here $2.346744/0.301029 = t$ I decided to use a calculator to know the value of $t$ just for fun. Using windows 10 calculator I got the value of …
RaptorX
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Inverse Proportion on a graph

The force of attraction(F newtons) between two magnets is inversely proportional to the square of the distance , d centimetres , between the magnets . Sketch a graph to show relationship between force and distance on both axis that begins with 0. Y…
user337744
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Compounded interest quarterly

Calculate the compound interest earned when 8000 is invested for 9 months at 5% per annum compounded quarterly. I'm confuse with this question because compounded quarterly means that every 4 months interest will be earned? 4 + 4 = 8 months There…
user337744
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Profit and loss question

A shopkeeper buys $240$ pears for $60$ dollars . Some of these pears are bad and they are thrown away. The remaining pears are sold at $35$ cents each , thus making a profit of $19.80$ dollars . Calculate the percentage of pears that are thrown…
user307640
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