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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How to prove that $x \gt 0, y \gt 0 \Rightarrow xy \gt 0$

Show that, for every $x,y \in \mathbb Z$, we have: $x \gt 0, y \gt 0 \Rightarrow xy \gt 0$ I've tried this way: supose $x= \overline {(a,b)}, y= \overline {(c,d)}$. Then, $x \gt 0 \Rightarrow \overline {(a,b)} \gt \overline {(0,0)} \Rightarrow a \gt…
Walter r
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What is the square root of 1 cm

If $1$cm = $.01$m then shouldn't the square root of $1$cm = the square root of $.01$m but the square root of $1$ = $1$ while the square root of $0.01$ = $0.1$ So my dilemma, is the square root of $1$ centimeter = $0.01$ meters or $0.1$ meters?
Steve
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Add 2 Figures that each have a margin of error

How would I add two figures that each have a margin of error. i.e. 3.5 +/- 10% + 1.5 +/- 10% With answer being the appropriate number with the appropriate margin of error. Is the answer 5 +/- 10%? How would you calculate it if the margin of error…
user105679
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Sequence of the form $pn^2+qn+r$

A sequence 192, 360, 576 is formed by multiplying the corresponding two different arithmetic progression. What is the eighth term of the sequence? Solution says that answer will be of the form $pn^2+qn+r$. Why is this, and how can I find it?
Sherlock Watson
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calculate the loss to shop owner

A customer purchases clothes worth 200 Rupees from a shop. customer gives 1000 Rupee note. Since shop owner does not have change, he collects change (100 * 10 notes) from the neighbor shop and gives 800 rupees back to the customer. After few hours…
Vinayak Kini
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Intuitive explanation of sum^2

The following equation can be easily proved with induction (using $(a+b)^2=a^2+2ab+b^2$): $$\left(\sum\limits_{i=1}^n a_i\right)^2 = \sum\limits_{i=1}^n a_i^2 + 2\sum\limits_{1\leq i
zvisofer
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Writing a number as power of two

Number of powers of two needed to be added to the given powers of two to write the (sum of given powers and added powers of two)number of the form $2^k-1$ where $k$ is any integer. Okay, let me explain the question. Suppose you are given: $2^0 , 2^1…
vaidy_mit
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A problem on generalization of a solution

Consider the following question: Two cars A and B start simultaneously from two different cities P and Q respectively and move back and forth between the cities.(As soon as car A reaches city Q it turns and starts for city P and as soon as it…
Suy
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Easy Algebra Question

Its been too long since my highschool algebra class, and now I need those skills again. I'm reviewing all my math on khanacademy.org but I need this answered sooner than that. What algebraic property(s) makes the transformation between the following…
TheEntity08
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Where do variables outside of a square root go?

This is a formatting question. Example, $\sqrt{4}x^2 \text{ or } x^2\sqrt{4}$. Which is less ambiguous? Is there a style guideline for things like this?
iamreptar
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Help with Math Formula

I'm trying to understand this marketing formula but even when I try using a calculator I end up with the wrong answer of $0.01 CPC = Cost Per Thousand Banner Views (CPM) / Average Banner Clickthrough Rate (CTR) x 1000 If you're paying 1 dollar per…
Joe Bobby
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Calculating money and some others of lifes aspects!

I get shy when I sometimes can't add for example 15 + 23 very quickly. It does not happen just with these numbers but also with others except very simple ones such as 4 + 4 or 10 + 14, these are easy. So what do you recommened me to do exactly?
Hadeel Web
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When the sum of 455 and four times a positive number is subtracted from the square of the number, the result is 117. Find the number.

When the sum of $455$ and four times a positive number is subtracted from the square of the number, the result is $117$. Find the number. Any thoughts on what to do first? How to set up a formula maybe?
Aaron
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Simple equation.

I was browsing the web and came across this question: 10 + 10 x 10 I would argue BODMAS would apply, using high school math. B rackets, O rder D ivision M ultiplication A ddition S ubtraction I would place the brackets so: 10 + (10 x…
user93502
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How many digits are there in the number $200^{2010}$?

How many digits are there in the number $200^{2010}$? I have tried to re-write it as $(2\cdot 100)^{2010} = (2\cdot 10^2)^{2010} = 2^{2010} \cdot 10^{4020} = 1024^{201} \cdot 10^{4020} = 1.024^{201} \cdot 10^{4623}$. But how do I write …
user30523
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