I’m going exponential e, I never came across it until I started learning higher maths at UTQ after high school.
It was everywhere.
Pi of course is another contender.
The square root of minus 1 is only really a mathematical get out card and is represented by a couple of letters of the alphabet depending on the discipline context.

Any other contenders of note?

Logarithms seem to be pretty important,

So sadsacks will tell you it is “the golden ratio”, phi, about 1.618 = 0.5+ sqrt(1.25), which pops up here and there.

But basically I am with you, e is magical.

Peak Warming Man said:

Any other contenders of note?

Rule of 9.

is c a physical constant or a mathematical one?

JudgeMental said:

is c a physical constant or a mathematical one?

Physical.

Euler’s number gets my vote as well.

The derivative of e^x = e^x

The Integral of e^x = e^x

Ya just cannot get sexier than that.

Just to avoid agreeing with PWM, I’m going for pi.

1

That’s just derived from e anyway.

The Rev Dodgson said:

Just to avoid agreeing with PWM, I’m going for pi.

I just checked and found that:

The integral of π^x = (π^x)/ In(x)

The derivative of π^x = π^x In(x)

Bugger that, I’m sticking with ‘e’,way easier to remember.

dv said:

That’s just derived from e anyway.

:)

0

is my choice

Dropbear said:

0

is my choice

Classic, timeless

Dropbear said:

0

is my choice

→ see dv’s previous response.

not sure it really classifies as a ‘constant’, but infinity is pretty useful

probably a better question is what branch of mathematics is most useful…

algebra? calculus? geometry? …

I’ve always been partial to “X”

I like pi.

wookiemeister said:

I’ve always been partial to “X”

as in the algebraic variable ‘x’ ??

Not quite related but Pythagoras theorem is useful and helped with the step measuring 2 dimensional space to 3 dimensional and 4 dimensional space even though the basic formula was jiggled a little along the way. How would we have managed without pythag theorem.

Pi is important – I agree as well.

diddly-squat said:

wookiemeister said:

I’ve always been partial to “X”

as in the algebraic variable ‘x’ ??

There’s nothing wrong with nominating a variable as your favourite constant :)

diddly-squat said:

wookiemeister said:

I’ve always been partial to “X”

as in the algebraic variable ‘x’ ??

oh you know it baby

can a repeating decimal be counted… like the expression of 1/3 and 2/3 expressed as decimals becoming infinite numbers 0.3333333 r and 0.6666666 r?

diddly-squat said:

probably a better question is what branch of mathematics is most useful…

algebra? calculus? geometry? …

Probably basic arithmetic, followed by trig.

sibeen said:

diddly-squat said:

probably a better question is what branch of mathematics is most useful…

algebra? calculus? geometry? …

Probably basic arithmetic, followed by trig.

what do you mean with basic arithmetic..?

literally the number line 0, 1,2,3,4,5,6,etc etc
and conversely 0,-1,-2,-3,-4,-5,-6 etc etc ?

monkey skipper said:

sibeen said:

diddly-squat said:

probably a better question is what branch of mathematics is most useful…

algebra? calculus? geometry? …

Probably basic arithmetic, followed by trig.

what do you mean with basic arithmetic..?

literally the number line 0, 1,2,3,4,5,6,etc etc
and conversely 0,-1,-2,-3,-4,-5,-6 etc etc ?

Yeah, the Real Numbers (ℜ) and the basic arithmetic functions – + – x / etc

The two constants I have to deal with right now are 1/10 and 1/11.

I believe the government finds those quite useful.

The Rev Dodgson said:

The two constants I have to deal with right now are 1/10 and 1/11.

I believe the government finds those quite useful.

GST

Peak Warming Man said:

I’m going exponential e, I never came across it until I started learning higher maths at UTQ after high school.
It was everywhere.
Pi of course is another contender.
The square root of minus 1 is only really a mathematical get out card and is represented by a couple of letters of the alphabet depending on the discipline context.

Any other contenders of note?

Other contenders: 0, 1, 2, 3, 4, 10, sqrt(2).
Look here: http://mathworld.wolfram.com/Constant.html
Pi, e and sqrt(2) are the three I use most often.
I sometimes use gamma, phi and i.

Follow on question, what are the most useful physical constants?
c and G are the two I use most often, but I also use the Stefan-Boltzmann constant sigma surprisingly often, and sometimes the molar gas constant R. I’ve never needed to use the value of h.

diddly-squat said:

probably a better question is what branch of mathematics is most useful…
algebra? calculus? geometry? …

Hmm, looking up the branches. http://en.wikipedia.org/wiki/Areas_of_mathematics
Arithmetic is most useful, followed by “elementary algebra” then geometry. Perhaps probability and statistics next (including stochastic processes) then calculus.
I don’t see “graphs” listed as a branch of mathematics but the old XY plot is extremely useful.
I use “mechanics” quite a lot. My work has involved a lot of “fluid mechanics”.
I dabble in set theory, manifolds,
One the other hand, what I’ve been doing most often lately is recreational mathematics (sudoku etc.)

I’ve never considered “analysis” to be a branch of mathematics. But looking it up http://en.wikipedia.org/wiki/Mathematical_analysis I find that I use every single part of it, including limits, infinite series, and very often “numerical analysis”. I have a patent that involves a practical application of “functional analysis”.

Note that there’s a huge difference between “elementary algebra” and “algebra”. I once went into a bookshop and said “I don’t remember the title but it’s about groups, fields and rings”. When the book was found, “topics in algebra” the assistant gave me a look I shall never forget, she was looking in the sports section.

mollwollfumble said:

Follow on question, what are the most useful physical constants?
c and G are the two I use most often, but I also use the Stefan-Boltzmann constant sigma surprisingly often, and sometimes the molar gas constant R. I’ve never needed to use the value of h.

I never use c or G directly, but there are many days when I use g in millions of equations (at least my computer does).

Does pi count as a physical constant when it is used in solving a physical problem?

I had it in my head somewhere that the fine structure constant determined a lot of others ..

For me the big one’s are e, π, j, √2 and √3.

Death and taxes

Dropbear said:

I had it in my head somewhere that the fine structure constant determined a lot of others ..

Yes. Wikipedia gives four ways to calculate the fine structure constant from other fundamental physical constants.

Statistics are loved in the public service, 9 out of 10 public servants know this.

sibeen said:

For me the big one’s are e, π, j, √2 and √3.

Good point, but I tend to use √5 more than √3 because √5 = √1^2 + 2^2.
√5 is also very useful in the dimensions of the pentagon.

mollwollfumble said:

sibeen said:

For me the big one’s are e, π, j, √2 and √3.

Good point, but I tend to use √5 more than √3 because √5 = √1^2 + 2^2.
√5 is also very useful in the dimensions of the pentagon.

Just about the only one I use is π. Volume of tanks or concrete.

mollwollfumble said:

because √5 = √1^2 + 2^2.
.

BLINK

Test post for mathematical symbols.
∑∫πρθ→ω≠∞
Same symbols different way of writing them.
Σ∫πρθ→ω≠∞

√5 = √(1^2 + 2^2)

mollwollfumble said:

√5 = √(1^2 + 2^2)

one squared??

diddly-squat said:

mollwollfumble said:

√5 = √(1^2 + 2^2)

one squared??

I’m sure he meant cubed :)

sibeen said:

diddly-squat said:

mollwollfumble said:

√5 = √(1^2 + 2^2)

one squared??

I’m sure he meant cubed :)

1^(almost infinity), probably.

But seriously, what is wrong with 1^2?

sibeen said:

diddly-squat said:

mollwollfumble said:

√5 = √(1^2 + 2^2)

one squared??

I’m sure he meant cubed :)

of course…

smacks head

The Rev Dodgson said:

sibeen said:

diddly-squat said:

one squared??

I’m sure he meant cubed :)

1^(almost infinity), probably.

But seriously, what is wrong with 1^2?

I prefer the simplified form… you know… 1

diddly-squat said:

I prefer the simplified form… you know… 1

I see no reason to discriminate against x^2, just because x = 1 :)

Slightly off-topic, but
∀x∈ℝ x⁰=1;
∀x∈ℝ 0^x=0;
So what is 0⁰?

The Rev Dodgson said:

diddly-squat said:

I prefer the simplified form… you know… 1

I see no reason to discriminate against x^2, just because x = 1 :)

sure… but in that instance x also equals -1

btm said:

Slightly off-topic, but
∀x∈ℝ x⁰=1;
∀x∈ℝ 0^x=0;
So what is 0⁰?

Defined as being equal to 1.

sibeen said:

btm said:

Slightly off-topic, but
∀x∈ℝ x⁰=1;
∀x∈ℝ 0^x=0;
So what is 0⁰?

Defined as being equal to 1.

That makes sense. If you graph y=x^x it approaches 1 (from above.) (I’ve just done that!)

btm said:

Slightly off-topic, but
∀x∈ℝ x⁰=1;
∀x∈ℝ 0^x=0;
So what is 0⁰?

Second equation is wrong
-1∈ℝ but 0^-1≠0

In Oz business it is 0.9090909…..when it comes to GST.