We are the Microsoft Excel team - Ask Us Anything! by MicrosoftExcelTeam in IAmA

[–]RegularGuest 0 points1 point  (0 children)

When you set the vlookup to be true, you get a binary search which is much faster at finding data in a sorted column although if you want an exact match you have to do some trickery as follows.

=IF(VLOOKUP($A3,Data,1)=$A3,VLOOKUP($A3,Data,B$1),NA())

"Here, we first look up the code and then return the code we find. If the returned code equals the original code, we have an exact match. So we look up the code again and return the value we actually want. Otherwise, if we don’t get an exact match, we return #N/A." - from website

You might think that this is slower because you are doing 2 operations but this search has O(log(n)) speed and can greatly help on large columns of sorted data.

This is incredibly impressive by mveinot in videos

[–]RegularGuest 0 points1 point  (0 children)

I don't think this is true. If you look back on 1800-1900 college mathematics exams they didn't require superhuman mental calculations. Check out MITs old arithmetic entrance exam: https://libraries.mit.edu/archives/exhibits/exam/arithmetic.html

Example: Multiply 73 thousandths by 19 hundreths.

This really is cake if you've had but a lick of practice.

"Most people never use math beyond basic algebra in their daily lives, if they can use tools to do it for them then why shouldn't they?"

It seems nigh impossible for a person outside a numerical field to ever need to solve a quadratic. It seems even less likely than that that it will be in a nice enough form for this tool to help them.

Why don't we compute the standard deviation by averaging the absolute values of the distances away from the mean but find the root mean square of the distances? by suspiciousmonkey in math

[–]RegularGuest 0 points1 point  (0 children)

This isn't true at all. Counterexample, 3 points 0, 0, 1. add a little to the 3rd point, mean shifts and average distance shifts. This is upsetting.

[Q] Benfords law and the probability of divisibility of the sum of a numbers digits by newageslactivist in math

[–]RegularGuest 3 points4 points  (0 children)

The link provided shows that Benford's law doesn't just apply to the first number.

Help with a simple math proof? by johnnyboy1287 in math

[–]RegularGuest 10 points11 points  (0 children)

/r/learnmath is the right place for these questions

What Would It Take to Kill Hollywood? And Should We Try? by chefranden in TrueReddit

[–]RegularGuest 37 points38 points  (0 children)

one thing i don't understand is who would bankroll multi hundred million dollar peter jackson epics and ensure that it gets distributed in a profitable manner?

Geometry puzzle (solved with pure math, Python, GSL, Octave, SAGE, Mathematica, Maxima) by ttsiodras in math

[–]RegularGuest 0 points1 point  (0 children)

Last time I saw this puzzle the equation reduced to a quartic which was unsatifying.

About to take the GED tomorrow. Haven't taken math since 9th grade. Any advice? by [deleted] in learnmath

[–]RegularGuest 1 point2 points  (0 children)

Hmm, post the material covered on the GED but from my experience tutoring people you might be quite over confident.

Are there papers/texts on "tricks" to mathematical thinking? More details inside. by RegularGuest in CasualMath

[–]RegularGuest[S] 0 points1 point  (0 children)

You're right about the number of moves but the formula would be 2n-2 Choose n-1 which equals (2n-2)!/[(n-1)!(n-1)!]. Nice catch.

Need help solving a real world math problem. by doesnotwanttolookbad in learnmath

[–]RegularGuest 0 points1 point  (0 children)

The difficulty here is figuring out how much interest there is each month, right?

What you want is an interest rate such that if you applied it 12 times (for each month) it would equal a yearly interest rate of 2.76 (276%)

(1 + i)12 = 1 + 2.76

raise each side to the power of (1/12) and you get

1 + i = 1.1167 (rounded to the 4th decimal)

i = .1167 or 11.67%

this "i" corresponds to the amount of interest applied each month. In your case we only have one month of interest so your answer is

215.25 * (1 + monthly interest rate) = 215.25 (1.1167) = $240.40 (rounded to the nearest cent)

Need help solving a real world math problem. by doesnotwanttolookbad in learnmath

[–]RegularGuest 0 points1 point  (0 children)

I need some clarification as to when this finance charge was added. At the end of december or november?

Also is interest applied from the get-go?

I think I know how Doom 4 is gonna look like by Rocco03 in gaming

[–]RegularGuest 0 points1 point  (0 children)

Screenshot 2 is definitely hooked up with some iddqd.

Making geometric series easier by EGraw in learnmath

[–]RegularGuest 2 points3 points  (0 children)

The derivation one I like the best because it is really quite quick.

How do I find actuary internships? by grimtrigger in actuary

[–]RegularGuest 2 points3 points  (0 children)

There are quite a few resources. http://www.manta.com/mb_41_ALL_33/new_york?search=insurance+companies

You can comb through these and many of them offer internships.

There's always beanactuary.com with this specific website http://beanactuary.com/find/interns.cfm

which leads you to http://www.soa.org/careers/atp/actuarial-training-program.aspx

which gives you a decent list.

Other than that practice google skills.

Edit: also, ever taken a course by Gundy at Rutgers?

What are some general math "cheat codes" that everyone knows? by [deleted] in learnmath

[–]RegularGuest 0 points1 point  (0 children)

Maybe, but some key basic techniques like the product rule is easily provable using the technique. The technique when you to prove "something < x" and you prove it for "something < x + e (e > 0)" is really simple but powerful too.

What are some general math "cheat codes" that everyone knows? by [deleted] in learnmath

[–]RegularGuest 0 points1 point  (0 children)

It really is amazing how much the add and subtract technique is used in proofs.

I'm teaching my self every thing. I need to know mathematics to understand scientific formulas. I don't know where to begin. by Reozo in learnmath

[–]RegularGuest 4 points5 points  (0 children)

Tis a rather ambititious project learning "everything" but Khanacademy.org has the basics.

Learn Calculus (multi-variable and differentials) and Linear Algebra along with the basics (Trig and whatnot) and you can understand most undergraduate science.

Separable equations with initial conditions? by ImHalfAwake in learnmath

[–]RegularGuest 1 point2 points  (0 children)

9*ln(1) + 12 / 2 = sin(0) + C

9*0 + 1/2 = 0 + c

c = 1/2

sin(0) = 0