Maths stuff.

Been watching Dave Gorman's Modern Life is Goodish on Dave.  Its either that or bastard Casualty and to be honest its no contest at all.  Its a good poke at modern life, and this week was about market research in all its glory, if you can find clips of this, the segment on YouGov is a real eye opener.  Its got me thinking about some maths based stuff (yes America it has an S at the end unlike Lego which doesn't) and a few ads and things. Oh and you'll also learn some stuff about how to do base maths but not division as I can't divide.

The first up is various beauty product ads, if you note the small print on the bottom of them, they give trial sizes (which are often small) expressed as a percentage of people taking part.  Take for instance some junk from L'Oreal, a new Jizz facial cream with new amino acid a (it doesn't exist of course), they'll give the trial size, lets say 186 women and a percentage, oh put it at 86% of those that were happy with it.  

Now of course on TV that stuff is blink and miss it gone but we have numbers written down so we can work it out.  Warning for those maths averse its going to get a lot harder, you will want a pencil and paper at hand to work stuff out, hopefully you'll learn stuff.  I had to work this out for myself though some was taught at school.

10% of 186 is 18.6 (top tip. to find 10 percent of anything follow these rules.  
 How to find 10% of anything.
If it ends in anything other than a 0 put a dot between the last two digits.
If it ends in a 0 simply remove the end 0 to find 10% of everything.
Oh and if  your number is just a single digit put 0. in front of it. this should get you 10% of anything.

You can then multiply 18.6 by 8 to get this
18.6
x8
-----
148.8
-----
10x8= 80 Start with the largest first this is the 1 that makes up 18 as you can see its really a 10.
8x8= 64 Next start with the next largest.
0.6 x8 = 4.8 finally the lowest if its a number like this you can use normal multiplication 6x8 and add a dot between the 4 and the 8 to get the right result.
Finally with all the results in you can add them together.

80
64 +
  4.8 to get 148.8

Incidentally the way I add is no different except you should be looking for things to make 10 naturally. If you have a few numbers such as 8, 3, 7 and 2 you would add the 8 and 2 and 7 and 3 together to make 20.  In that case where there is no natural split you can make 10 out the 8 and 6 by taking 2 off the 6 and adding it to the 8 leaving 4 to add making it 14.

Now with 80% worked out you can find  out the remaining 6% by breaking that 186 into a 1% chunk and you do that the same way you did 10% except you place the decimal point behind the first number, in this case behind the 1 like this. 1.86.  If its a single digit you  put 00. in front of it.

You can multiply 1.86 by 6 to get this.
1.86
x6
 11.16
Which breaks down from the front like so.
6
4.80  remember that it'll need a decimal between the 4 and 8 here
0.36  this one requires a 0. in front of it to make it work.

Finally you can add together 148.8 and 11.16 to make 159.96.
which adds together like this.

148.8
  11.16
--------
159.96
--------
As you can see (and what those with calculators have worked out 5 paragraphs back) that it doesn't break down to a perfect number and in this case the ad would round it up to the nearest whole number.  So the tag line would be: 86% of 180 women tested 160 liked new L'Oreal Jizz facial to the other.