A Kilo of Nails

[richarta]

If you did have 100 nails to weigh, they would weigh 149 grammes

You actually counted them out and weighed them for me?

 

[madmattman]

if like me you cant add 2 and 2, then you could just buy a one kg bag of nails adn count them all. gives a bit of an idea.

 

[mildmanneredjanitor]

OK Adam,

(question from me, not daughter!) what is the maths formula to remove VAT?

Can't remember for the life of me how to do it, seem to remember it being quite simple tho.

I luv this site!

 

[AdamW]

Well, if you have something that costs say, £100+VAT and you want to see what the cost with VAT is, you add 17.5%. So, you multiply by 1.175. Then you get £117.50 INC VAT

If you want to do the reverse (as you ask) then you just do it in reverse. That is, you divide your VAT inclusive cost by 1.175.

So, something that costs £117.50 INC VAT:

117.50/1.175 = £100.00

 

[2scoops0406]

Well, I think my method is still better, now I'm going to stick my fingers in my ears and go nah nah, not listening.

P.S I offer no defence of my industry

 

[Stod]

Well, if you have something that costs say, £100+VAT and you want to see what the cost with VAT is, you add 17.5%. So, you multiply by 1.175.

I find it easier to divide by 40 and multiply by 47. You can sometimes do this in your head.

Similarly, but less easily, you can remove VAT by multiplying by 40 and dividing by 47.

 

[AdamW]

Doing it in my head I have always taken 10% of the cost, multipled that by 1.75 and added it to the original figure.

But I will remember that 47/40 method, can never hurt to have a different method up my sleeve

 

[haveabash]

Hi all,
new here but love it already. I'm an electronic engineer, and so apparantley useless at anything apart from driving a van and pushing buttons. That aside, my vat plan is this
if adding vat:
get 10% dead easy, divide by 10
then half it and add it on, another 5%
then half the 5% and add that on, another 2.5%
bingo 17.5%

is the same to remove, just do the same 10,5 and 2.5% and remove the total

I like it cos I can divide by 10 and by 2 fairly well. was never good at my times tables though

Lee

 

[MANDATE]

Hi Lee!
Youv'e missed an important point, you can't remove vat by deducting 17.5% of the new total.

 

[haveabash]

and how right you are, no wonder my end of month figures never add up properly
lol

will have to think of a new way, maybe invest in that calculator at last...

 

[pipme]

Adam's methodology regarding the nails, helps to ensure a full understanding of the problem ... Only then can you begin to look for some 'constants' which may provide greater simplicity.

Mind well what they were going to do to the guy who dropped two different sized cannon balls at the same time from the Leaning Tower of Pisa ... revealing that they hit the ground at the same time ... A few still do not believe that.

P

 

[AdamW]

That was Galileo was it not... Still, they would not hit at EXACTLY the same time, as the air resistance is the same yet the weight is greater for the heavier ball. Hence the heavier ball will hit the ground ever so slightly before the lighter one, but the difference will be within the experimental error (how good you are at dropping both at the same time).

The Apollo astronauts dropped a hammer and a feather on the moon, being in a near vacuum they dropped at the same rate, looks very strange to see that happen!

 

[pipme]

Galileo at the tower of Pisa.
I think in retrospect that one ball was iron the other wood.
Apparently twas one of Galileo's students who performed the experiment when Galileo was quite old and not the man himself .... But the old devil had also already explained that 'wind friction' or viscosity would play a part in causing a slight difference in the time to impact.
I think it is still seen as heresy ?

Oh, no it isn't ! Can anyone believe this next bit ?
His work was finally removed from the Inquisiton's banned book list in
1954. The validity of his scientific work was formally recognized by the
Roman Catholic Church in 1993.

Bag of nails to Galileo !!! wot a fred !

P

 

[benm]

6.02 x10^23

 

[AdamW]

6.02 x10^23

Avogadro's number?

Yes, the Inquisition were a bunch of g*ts. I reckon they had a part to play when Spain was deciding it's wiring regs... "An earth conductor?! Why, tis herecy!"