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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
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Using alternate order of operations

Let's pretend, for a second, that we used PEASMD instead of PEMDAS. That is, addition/subtraction and multiplication/division are switched. Is it possible to write: $$(a\times b)+c$$ without parentheses? EDIT: For example, the expression $(a\times…
Akiva Weinberger
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How do I explain why multiplying $0.8 \times 0.8$ is less than $0.8$?

I'm math is very rusty so forgive me for a trivial question. In my daughters home work she had the sum $4.8 \times 4.8$. Her thought process was to multiply $4 \times 4 =16$ and then $0.8 \times 0.8$ (which she arrived at $6.4$) and she added the…
user1226884
  • 53
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Why did Frank Drake choose these math equations for the Voyager Golden Record?

Not sure this belongs in this or some other community, but one of the images on the golden record is a brief snapshot of our decimal system and then a few math examples. Here is the image in…
user192382
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2 answers

Origin or author of 'Japanese Multiplication Method'

What is the origin or author of the method 1 shown in the following image? Notes Also known as Japanese Multiplication Method for Kids.
Paul Vargas
  • 91
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4 answers

What's the intuition for why repeated div and mod converts a number to another base?

This guide here tells how to base 10 number to binary. For example, for the first bit, you take $356_{10} \div 2 = 178 \, R \, 0$. Because the remainder was 0, the first bit is $0$ and we recurse this procedure on $178$. I would like to be able to…
jaynp
  • 2,151
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Prove that $5$ does not divide $52$

If I suppose that $5$ divides $52$, then there would exist an $ s \in \mathbb Z $ such that $ 5s = 52 $. There is no such s, because $5(10) = 50$, and $5(11) = 55$. I'm not convinced with this proof, because I beleive I'm missing an argument, ad I´m…
Trux
  • 1,489
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The unexpected, $\ 2^n$ is not of the form $2xy + x$?

When testing polynomials for items of an integer sequence, I find that $2^n$ is not of the form $2xy + x,\ n,\ x,\ y \in \mathbb N.\ $How to prove this?
miket
  • 1,069
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A book asks me to prove a statement but I think it is false

The problem below is from Cupillari's Nuts and Bolts of Proofs. Prove the following statement: Let $a$ and $b$ be two relatively prime numbers. If there exists an $m$ such that $(a/b)^m$ is an integer, then $b=1$. My question is: Is the…
Andrew Liu
  • 333
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Why isn't the zero after the decimal in $0.01$ significant?

Why isn't the zero after the decimal in $0.01$ significant? Although it is pretty obvious that the zero before the decimal is insignificant, I don't understand why the zero after the decimal is not significant.
Shaurya Gupta
  • 4,339
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what does $-2^2$ evaluate to?

What does $-2^2$ evaluate to? My wife is upgrading her math & I'm quite uncertain how to answer. is it the same as $(-2)^2$ or is it the same as $-(2^2)$? at the heart of this is whether the minus sign is associated with the 2 or the expression…
x-ray
  • 43
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5 answers

Why is $-a \times -b = ab$?

This might be a bit of a meta-mathematical question (if there is such a thing as meta-mathematics) but it confuses me slightly. I think of multiplication (whether rightly or wrongly) as recursive adding. For example, $2 \times 4$ is just adding 2…
ApprenticeHacker
  • 486
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2 answers

Arithmetic? Logical/Boolean/Bitwise operations?

I'm trying to convey to some folks some logical and bitwise operators such as AND, OR, XOR, &c in programming languages such as C &| Java. Though these I guess could be considered "boolean" operators there is no "Boolean Algebra" in here, just the…
Jé Queue
  • 143
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Is there a non-guessing way to do a simple division operation?

I'm a newbie in math and while doing some exercises and reviewing basic operations I got myself thinking about something that is funny, at least. If you want to divide, let's say, 13570 by 14 what you should do is: start by taking 1 and see if you…
Dulce
  • 43
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A prize of $27,000 is to be divided among three people in the ratio 3:5:7. What is the largest share?

This is not homework; I was just reviewing some old math flash cards and I came across this one I couldn't solve. I'm not interested in the solution so much as the reasoning. Thanks
oldmanharry
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