6
votes
3answers
104 views

Confused about the $\pm$ sign?

I have multiple questions about the $\pm$ sign, since it seems to confuse me in general... Question 1: Say I have $15=\pm(a+x)$, Can I use the distributive property so it becomes $15=\pm a \pm x$? ...
0
votes
1answer
41 views

Is there a more rigorous method of notating arithmetic?

Is there a method of notating arithmetic that presents the transformations more explicitly than the standard method? For example. Someone using the standard method might present their solution ...
1
vote
1answer
98 views

is the decimal notation the “right” notation for arithmetic?

I am considering here the pre-decimal notations such as Roman numerals, Egyptian numerals etc. It seems reasonable that these must all be equivalent. And it seems that decimal notation (i.e. ...
1
vote
2answers
256 views

What does P(A U B) mean, in terms of real values?

I can't find a proper summary or reference of how to translate formulas in probability notation to arithmetic notation (i.e. when using real values). For example, if $P(A) = .7$ and $P(B)=.35$, what ...
1
vote
3answers
91 views

How does ZFC describe addition?

Surprisingly, the Wikipedia article on addition doesn't contain the answer. I looked elsewhere online for it, but didn't find it. Intuitively, the cardinal of the union of two sets seemed ...
3
votes
1answer
48 views

Is there any way to write this number with these limits?

Is there any way to write this number: $$ \frac{17+15\sqrt{5}}{7+15\sqrt{5}} $$ Just using the digits $1$, $4$, $7$, $8$, $9$ once each with the following criteria: A maximum of two square root ...
9
votes
4answers
212 views

Why are the order-of-operations conventions good?

Children are sometimes taught silly mnemonics like "PEMDAS" to remember conventions on order of operations. (I never heard of "PEMDAS" until long after graduating from college, as far as I can ...
1
vote
3answers
212 views

Order of operations in rotation matrix notation.

I'm trying to convert this equation to C# but I'm not a mathematician and I find math notation ambiguous: See the first matrix in this article: http://mathworld.wolfram.com/RotationMatrix.html ...
0
votes
3answers
105 views

Dumb percentage question?

Why do we multiply by 100 while calculating percentage ? example : 2/100 * 100 =2%
0
votes
2answers
72 views

order of operations division

Very dumb question: What is the order of operations in the following: PEMDAS a/b+c = a : b + c (where ":" is the division symbol) 7/1+6 or 7:1+6 in the example below is it 1 or 13?
5
votes
2answers
311 views

Powers in ASCII text

I have a problem reading a discussion forum post. Namely, in the ASCII text, is 2^3^4 the same as $(2^3)^4$ or $2^{3^4}$?
1
vote
1answer
108 views

Correct precedence of division operators

Say i have the followingv operation - $6/3/6$, i get different answers depending on which division i perform first. $6/3/6 = 2/6 = .33333...$ $6/3/6 = 6/.5 = 12$ So which answer is correct?
2
votes
3answers
561 views

What is the “status” of the rule that multiplication precedes addition.

What is the source, or "status", of the rule that multiplication is performed before addition? Is it a definitive property of $\mathbb R$, a property that can be derived directly from the definition ...
0
votes
2answers
129 views

Radix point notation and significant digits

So, we represent numbers usually in a form of a sequence of digits where each one of them multiplies the power of a base: $13.2 = 1 * 10^1 + 3 * 10^0 + 2 * 10^{-1}$ So that much is clear, perfectly. ...
0
votes
2answers
490 views

bitwise operations

so my question is what is the order of operations for bitwise operators << & | and also to see if my logic is right with the problem below (x03 << x08)+ x00 = 300 ...
10
votes
1answer
1k views

What is mathematical basis for the percent symbol (%)?

Percent means 1 part of 100 or 1/100 and is indicated with %. Per mille means 1 part of 1000 or 1/1000 and is indicated with ‰, so it seems that these symbols indicate the mathematical operations ...
3
votes
3answers
7k views

What is “multiplication by juxtaposition”?

I was reading http://www.purplemath.com/modules/orderops2.htm it shows = 16 ÷ 2[2] + 1 (**) ... = 5 The general consensus among math people is that ...
9
votes
4answers
16k views

What is 48÷2(9+3)? [duplicate]

There is a huge debate on the internet on $48÷2(9+3)$. I figured if i wanted to know the answer this is the best place to ask. I believe it is 2 as i believe it is part of the bracket operation in ...
5
votes
4answers
595 views

Long division notation (census of nations)

The Wikipedia article on long division explains the different notations. I still use the European notation I learned in elementary school in Colombia. I had difficulty adapting to the US/UK notation ...