i just learnt some new maths(!)

[bigegg]

I'm GOOD at maths: i have a GCE o level, two GCSEs, 5(!) A-levels [1], plus a BA from the OU which is 90% maths based.
I also read a fair amount of published maths/science papers.

I just read an article which told me something i never realised, but is, in hindsight, obvious:

x% of y = y% of x

so instead of trying to calculate (for instance) 4% of 75, calculate 75% of 4.
*much* easier to do in your head!

hope someone finds this as interesting / useful as I did!




[1]
Pure Maths
Applied Maths
Statistics
Pure + Applied
Pure + Stats

 

[Seadog]

I need to think about that. Once I've finished watching Endeavour, that is.

 

[Screwdriver]

I'll be damned. So it is. Never knew that either and it's bound to come in handy.

 

[R-D-R]

I can't write very well (with my Hands) and I'm useless at spelling and grammar but I am pretty good at other things including mathematics. I came across this in my news feed the other day and thought "oh yeh that's nifty !"

 

[rtbcomp]

I failed my degree in electronic engineering because the maths in physics was more difficult than the maths in maths.

 

[bigegg]

I failed my degree in electronic engineering because the maths in physics was more difficult than the maths in maths.

tensor calculus was my downfall

 

[roofman]

tensor calculus was my downfall

just getting to school was mine

 

[Seadog]

Just writing it down it's obvious. I don't ever remember being taught that.

 

[bigegg]

Just writing it down it's obvious. I don't ever remember being taught that.

me neither

 

[rtbcomp]

tensor calculus was my downfall

I've recently bought a copy of "Calculus for Dummies" and just realised I can't read.

 

[ChrisW8]

Easy peasy stuff......

My mates lad works in CERN....

https://atlas.web.cern.ch/Atlas/GROUPS/PHYSOFFICE/higgs-preview.pdf

Some light reading there !!!!

 

[graffian]

4*75/100=75*4/100

tensor calculus was my downfall

The Metric Tensor!
Both general relativity and condensed matter used them. I can't remember any of it at all.

But I did find a use for matrices, translation and rotation of coordinates when milling.

 

[JulieandTony]

4*75/100=75*4/100

Yeah,

I can't understand the fuss, it's people realising that 4 x 75 is the same as 75 x 4

How is that a revolution??

 

[R-D-R]

I know that’s what all the excitement is about it’s been staring us in the face all this time :-)

 

[Tangledfeet]

Some 25yrs ago it was pointed out to me why VAT (at the time) was 17.5% - mind blown!

Take ten percent, half it, half it again and add the three together.

 

[Screwdriver]

Yeah,

I can't understand the fuss, it's people realising that 4 x 75 is the same as 75 x 4

How is that a revolution??

Probably because you're not understanding the maths either.

The correct equivalent is that 0.04 x 75 is (of course) the same as 4 x .75

You are mistaken if you think you can simply ignore the order of operations in converting a percentage into decimal. The actual mathematics is trivially simple but the equivalence is certainly not something that I have ever considered previously (and I did not fail my electronics degree).

 

[frank horton]

I'm just dumb..........
but I can rebuild a gearbox in the dark........hahaha.....which is of fat use......

 

[JulieandTony]

Probably because you're not understanding the maths either.

The correct equivalent is that 0.04 x 75 is (of course) the same as 4 x .75

You are mistaken if you think you can simply ignore the order of operations in converting a percentage into decimal. The actual mathematics is trivially simple but the equivalence is certainly not something that I have ever considered previously (and I did not fail my electronics degree).

Ok to be pedantic it's

4 x 75 then devide by 100 is the same as 75 x 4 then devide by 100

It's such a simple mathematical concept in terms of the order of execution I didn’t think it was worth explaining...

2 x 3 is the same as 3 x 2
(2/100) x 3 is the same as 2 x (3/100)
(2 x 3)/100 is the same as (3 x 2)/100
(2 x 3)/100 is the same as (2/100) x 3

And so on

And why we have to add this I don't know, but I didn’t fail my degrees either.

 

[8ob]

I'm GOOD at maths: i have a GCE o level, two GCSEs, 5(!) A-levels [1], plus a BA from the OU which is 90% maths based.
I also read a fair amount of published maths/science papers.

My eldest daughter has a masters in mathematics but she still can wort out this equation

Dont save + spend too much = Reliant on bank of Bob

Bob

 

[rtbcomp]

Ok to be pedantic it's

4 x 75 then devide by 100 is the same as 75 x 4 then devide by 100

It's such a simple mathematical concept in terms of the order of execution I didn’t think it was worth explaining...

2 x 3 is the same as 3 x 2
(2/100) x 3 is the same as 2 x (3/100)
(2 x 3)/100 is the same as (3 x 2)/100
(2 x 3)/100 is the same as (2/100) x 3

And so on

And why we have to add this I don't know, but I didn’t fail my degrees either.

Multiplication & division come first, then addition unless there are brackets, in which case the terms in the brackets are calculated first. Spelling comes last.

So 5*6+7 = 30+7 =37
but 5*(6+7) = 5*13 = 65