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.

6283 questions
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Prove that if $N =\overline {xyz}\in\boldsymbol N$ (natural number) and if $x+y+z=9$ then $9$ divides $N$.

Prove that if $N =\overline {xyz}\in\boldsymbol N$ (natural number) and if $x+y+z=9$ then $9$ divides $N$. My try: $100x+10y+z=(99+1)x+(9+1)x+(10-9)z=99x+x+9y+y+10z-9z=9(11x+y-z)+x+y+10z$ Then I can't, help me please.
illyamatendi
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How to remember multiplication/times table of numbers greater than 12 but smaller than 21?

Is there any technique to permanently remember multiplication/times table of numbers greater than 12 but smaller than 21? For example, 13x1 = 13 .....through..... 20x10 = 200 ?
user6704
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How do I express a function that takes a set of values?

I have a function that I as a programmer would express like this in pseudo-code: myFunc(int[x0, x1, ... xn]){ return 1/((1/x0)+(1/x1)+...+(1/xn)); } How is this expression written in a mathematical form?
Alex
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Find the additive and multiplicative inverse of $-36$

Find the additive and multiplicative inverse of $-36$. I don't remember how to do these problems. If you can help that would be great. thanks!
Desiree
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Calculate desired profit given unit price and fee

This seems simple, but I'm struggling to find the answer... How much should I sell my apple for if I want to achieve the desired profit? Cost for me to buy the apple (A) = £10 Desired profit (B) = £3 Final customer price fee (C) = 10%
Eurig Jones
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A.P problem gaussian sum (average of terms explanation)

The question is "the sum of first n terms of an arithmetic progression,if the last term is given $S_n=\frac{n(a+l)}{2}$; what does "$\frac{a+l}{2}$" represent?
sreeram
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The sum of two numbers equals 318, express the product of the numbers according to the lowest

I didn't understand the question on the title, what am I supposed to do?
Delta
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Combining products of like terms in a division

I was seeing an example on a book which says that: $$\frac{t}{t(x+t+1)} = \frac{1}{x+t+1}$$ The instructions read: "combine products of like terms" What exactly is that? Why does it work and why didn't he just cut out the $t$ on the numerator and…
Delta
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How to calculate sum?

As you can see in my screenshot, I take 25% from score and sum the result which come up to 64. My question is that how can I obtain the same 64 from sum of full(175) and score (144)? I have tried something like 144*25*3/175, but I got 62. How can I…
Mawia HL
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Time and Work in Unitary Method

Let us suppose, A and B can do a given work in 12 and 18 days respectively. They work alternately for equal period of time. And A started the work. Now, what is the time taken by A and B to complete the job?
Avery
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Adding and subtracting roots

I have to find (a/b), b=(1-(√3/3)), a= (1+ (1/√3)) I know I can just punch this into my calculator. However, my teacher says we need to know how to add these and subtract these but just as said that, class was over. How can I add and subtract roots …
user3034084
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The sum of the discount is the discount of the sum

Suppose I have a till. I have a special that I give a 10 percent discount on all dinner meals. I want to know that if I calculate the discount on each dinner item and round up the discount and apply it to each meal, I will not lose money than if I…
Excalibur2000
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Arithmetic progression question I don't get

Given all of the three-digit numbers: 100, 101, 102, 103......999. A. out of these numbers, find out how many numbers can be divided by 3 without remainder. B. out of these numbers, find out how many numbers can not be divided by 3. A is easy: $$999…
Roy
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Convert clock time to one number?

I have a clock time in form of HH.MM.SS (hours, minutes, sec), I need to create a way to convert it to one number so that I can determent which time is bigger. for example 00.00.00 is the smallest 23.59.59 is the biggest 11.03.50 > 11.02.57 etc.. I…
user106453
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Bit Extention Rule in Calculators?

I have read Sign Extention Rule in Binary Numbers. I am having a problem.When I calculate Binary from Decimal from calculator(FX-992ES PLUS), it always appends 0's to the converted number. It is against the bit extension rule. Does it follow some…
user2857
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