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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A person went to market to buy 1.5 kg of dried peas having 20% water content. He went home and soaked them for some time and the water ...

A person went to market to buy 1.5 kg of dried peas having 20% water content. He went home and soaked them for some time and the water content in the peas become 60%. Find the final weight of the soaked peas . My approach : Since 1.5 kg contain…
Sachin
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Ratio and Proportion- Calculation Process

How we arrived for for following: $$\frac{441.66}{958.33}=\frac{441\cdot 3 +2}{958\cdot 3 +1}$$ I understand that $0.66$ is $\frac{2}{3}$ but want to know how we arrived at above relation.
Manuj Pandey
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10 + 67 × 2= ?, This question is causing a ruckus among my friend

Help! How would you solve 10 + 67 × 2? I solved by putting a bracket between 10 and 67. Then multiplying by 2 Like this (10 + 67)2 = 154 However, others insist it's 144 and I'm wrong.
mamus eferha
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Application of Telescope series in Rolle's theorem

In a solution to a certain Rolle's theorem problem, I have $x_k=a+\frac{k}{n}(b-a)$ and $$ 0=f(b)-f(a)=\sum_{k=1}^nf(x_k)-f(x_{k-1})=\frac{b-a}n\sum_{k=1}^n\frac{f(x_k)-f(x_{k-1})}{x_k-x_{k-1}} $$ How exactly does this work? I mean, let's say…
pikarin-g
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Running Balances and Expirations

I am trying to do some data validation on some account balances and was not sure if there was an easier way to do the math. So the rules for how the account balance works is you can earn into the account but it must be used within 365 days of…
Chad Portman
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Using average to calculate half

If 1 kid can eat 5 candies, 2 kids can eat 11 candies and 3 kids can eat 25 candies, then how much can 2.5 kids eat? I was thinking you calculate the average then use that but I cant just use the average right? I was thinking the average was equal…
Crazyluv
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Finding the remainder after division by $3$ is simple. What about the quotient?

A well-known simple trick for obtaining the REMAINDER after division by 3 is just the digital root of the dividend after division by 3, the digital root itself further simply obtained by first casting out 9's, then every digit pair that add up to 9,…
Beedassy Lekraj
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Why does average annual growth overestimate true growth rate?

If a company's shipments grew 100% from 100 to 200 and then in the next period fell 50% back 100, then the average annual growth rate would be 25%. But this growth rate is incorrect as you're back at your principal. A compounded annual growth rate…
N.P Singham
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Simplifying $3^2 + (-8\div2)$

Simplify $3^2 + (-8\div2)$. I know its not possible to divide $-8$ into $2$, so is there a way to make the 8 positive before working the problem?
Deriah
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pricing grid base calculation

I am useless at maths and have been trying to figure this out for ages. I am creating an website for a client which prices fabric based on square inch of material. Their supplier gave them the attached table but I cannot work out the base price…
Joseph Hunter
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Clock problem (hands becoming coincident)?

If it’s 4 o clock now, how many minutes will pass before the minute and hour hand are in the exact same place? In the solution, they come up with the formula: x=20+5(x/60), where x is the number of minutes that have passed. However, I am unsure how…
Jamminermit
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Largest possible difference between two numbers

I came across this practise question for a government numeracy test: What is the largest possible difference between 10 & 20 to 2 decimal places? What is the answer? As far as I can tell, the difference between 10 and 20 does not have a largest…
Nick
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Sharing moving costs with housemates

My housemates and I just moved and we've got a few costs associated with it as well as a refund from our previous house. Who owes who what. There are three of us. We are receiving a refund of 848.08 to be shared evenly amongst us. Person One paid…
Rhys Edwards
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Round up or down to nearest integer?

I'm not sure whether to round up or down to the nearest integer. The decimal is < 0.5, but the quantity refers to an amount of animals. So, is it common practice to round up or down when dealing with such physical quantities? I've been taught to…
Unsure
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Proof of X - (-A) = X + A. (Is it possible to prove?)

I have a problem with arithmetics. Is there is a proof that X - (-A) = X + A? Not just some analogy or "mind-trick". If so, could you tell me it or at least give some link or refer me somewhere? (may be a book, video, some website or whatever that…
Tim Solnze
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