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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.

6283 questions
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Unit conversion multiplication

This is going to sound like a really dumb question. At first I thought it was just my brain failing to function, but I can't work my mind around it. I'm using a problem to demonstrate the conceptual issue, but what I care about is why things work…
David Lalo
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Is there a difference between$ -(1000)$ and $(-1000)$?

Or are they equal? If they aren't, when one you use one and not the other?
Mjr001
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Sum of the number sequence that consists of multiplications of neighbor numbers

Say there is sequnce of number $A(i) = i * (i+1)$, i.e. like 1*2, 2*3, 3*4 and so on. Is there any formula that allows to compute sum of the first N such numbers?
ivan.ukr
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Is it possible to build a formula that prevents negative numbers?

I have a calculation that goes like this: $$\text{} - 100$$ As long as the result is a positive number it is acceptable. However, if the result is a negative number, I need the outcome to calculate to zero. A negative number is…
Michael Benjamin
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Inverse proportion

I am not sure how to approach this question, can I get some help? This is an inverse proportion question. $y$ is inversely proportional to the square of $x$. Find the percentage change of $x$ when $y$ is decreased by $36\%$ . Not sure where to…
user307640
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Problem on Time and Work

$A$ can do a piece of work in $10$ days, $B$ can do in $20$ days and $C$ can do in $30$ days. If $A$ is assisted by $B$ and $C$ turn by turn in alternate days respectively, in how many days the work might have been finished? My attempt; In $10$…
Iaamuser user
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Which of the following integers cannot be expressed as the sum of two prime numbers?

Please help me with this problem. I'm stumped! which of the following integers cannot be expressed as the sum of two prime numbers? A) $8$ B) $9$ C) $10$ D) $11$ E) $12$ According to the GRE book the answer is.... D) $11$
Hadi M
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Why does lattice multiplication work?

My brother (who is currently in 4th grade) is learning a technique called Lattice multiplication in school. It is a technique that involves taking two numbers, placing them on the outside of a square, and then computing the product. However, he said…
Chandler Freeman
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Sum based on sub-sums

Let's say, we have three numbers: $a, b, c$ but we know only their sums: $x = a + b, y = b + c.$ Is it possible to find sum $z = a + b + c$? edit - $a, b, c$ are natural numbers
user251405
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Fraction weights and weighted average smaller than sum op parts

I am considering a weighted average $\bar{x} = \frac{w_1x_1+w_2x_2}{w_1+w_2}$, where $x_1
Mavlast
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Fastest way to perform arithematic calculations

This is one of the questions asked for Junior Trader position at prop. trading firm. Perform the following operation. 4.3 * 0.58 + 2.0E-5 - 0.9 How can one perform calculations so fast in their mind? I tried learning vedic maths tricks (which are…
Saurabh Gokhale
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Struggling with a task with brackets

The task is to change brackets (operations, numbers and their positions should be remained the same) to make $F$ equal to $850$. $F = (1 + 2) \times (3 + 4) \times (5 + 6) \times (7 + 8) \times (9 + 10) \times (11 + 12) \times (13 + 14) + 15$
Artur Komendacki
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Puzzle: concatenation is three times product

The numbers A and B have three digits, while C is an odd number with 5 digits. Say you were asked to calculate the integer $(A B) /C$. Instead though you put A and B next to each other to form a 6-digit number D, and then divided by C. Your…
fosho
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What is the sum of the first $42$ terms of the sequence?

The sum of the first $14$ terms of an arithmetic sequence is $2014$. If the sum of the first $28$ terms of the same sequence is $2014$, what is the sum of the first $42$ terms of the sequence? I thought the sum would be the same ($2014$) since it…
Puzzled417
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How do you win the simple math game 20-19?

My friend (I think)made up this game called 20-19. The objective is to start at 20 and be the person to say one. You take turns, being allowed to say either 1 or 2 numbers. Ex: P1: 20, 19; P2: 18, and so on. Based on how fast the people who figured…
User
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