# Tagged Questions

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.

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### Is $3+2=5$ a equation?

Problem: Is $3+2=5$ a equation ? Solution As we know that that $3+2$ is a arithmetic expression. So $3+2 = 5$ is a arithmetic equation. But my friend said that $3+2=5$ is not a equation as it ...
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### Subtraction non-associativity when presented as addition

It's well known that the action of subtraction isn't associative: $(7-4)-1 \neq 7-(4-1)$ However, subtraction is simply the addition of negative numbers... so the inequality above can be ...
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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 ...
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### Sum of an unknown sequence (perhaps arithmetic or geometric)

The problem is stated as thus: Given a sequence $(a_n)_{n\geq 1}$, $$a_1+a_2+\dots+a_n = 1 + 2^{n+1}$$ for all $n$. Find $a_5$. This is all the information that is given.
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### The art of arithmetic [closed]

People doing arithmetic in a high level usually agree that there is an inherent beauty in numbers. They also often have trouble to find the words to describe how they feel and why they find arithmetic ...
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### Creating arithmetic expression equal to 1000 using exactly eight 8's and parentheses

I would like to find all the expressions that can be created using nothing but arithmetic operators, exactly eight $8$'s, and parentheses. Here are the seven solutions I've found (on the Internet) so ...
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### Find the last two digits of $2^{2156789}$

Find the last two digits of $2^{2156789}$. My try: As $2156789 = 4* 539197 + 1$ The unit digit of $2^{2156789}$ is similar to the unit digit of $2^{4n+1}$ which is equal to 2. But I'm unable to find ...
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### Can a piece of A4 paper be folded so that it's thick enough to reach the moon?

While procrastinating around the web I stumbled on a page that contained the image below, from cracked.com. I can't help but believe that this is false… Even though the article header says: ...