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docash1983
28th Feb 2008, 22:36
Hi Guys and Girls,

Firstly I apologise for a thread which has already been done to death. However, a couple of weeks ago I was browsing through the site and viewed a discussion about sprucing up on the old pre-assessment maths. There was one Australian mathematician (his name began with an “S” I believe), mentioned by someone on here who compared this gentleman’s book to Trachenburg. I managed to follow the link to this Guy’s book but that has disappeared from my computer, and cannot find the thread anywhere despite numerous searches. What I do remember from the few pages I accessed online was a method of long multiplication, by using nothing but the following method:

96 x 96

1st step looking at the numbers on the right of each number (the 6;s) what is missing to make the numbers upto 10 so that’s 4 here; so it looks like this:

96 x 96
4 x 4

2nd step times these together 4x4 = 16 these make the first two numbers

3rd step deduct the 4 beneath the right hand number from the top left hand number ‘96’ here to give you your second set of numbers, so:

96 – 4 = 92

Therefore the answer is 9216

However I can’t find the thread anywhere and I really want to get this book. Does anybody know who this guy is who wrote the book and the name of the book? I am sorry for the vague nature of the post, lack of information I have given to go off, and the long winded explanation above.

Many Thanks in Advance

Docash1983

KandiFloss
29th Feb 2008, 09:46
Hi,

Not sure about the book, but what might help you is to book yourself in for an hours tuition with a private maths tutor. If you're not sure where to find these have a look under teaching agencies in the yellow/white pages and they might have people who do private tutoring. Hope this helps?

airbuslit
29th Feb 2008, 12:20
docash1983

I don't think the method you have just mentioned is quite right. I tried it 32 x 32 and get 3064 as the answer when it should be 1024???:confused:

BlueSky747
29th Feb 2008, 12:31
The method is correct. Just you have to know what is behind.

-> 93 x 94

100 - 93 = 7
100 - 94 = 6

-> 93 x 94 = (93-6)x100 + 7x6 = 8700 + 42 = 8742
-> 7 x 6
-> or other way around: (94-7)x100 + 7x6 = 8700 + 42 = 8742

Important is you take the 100 as a base for the calculation. For 32 x 35 you can take the base 40. In general it works with "any" base.

For the book, have a look at the amazon and search for "mental math".

docash1983
29th Feb 2008, 17:54
Found It, finally. Now you can see what I mean by the calculation method which I set out. For any who are interested, the details are as follows

Bill Handley
Speed Mathematics: Secret Skills for Quick Calculation

http://www.amazon.com/Speed-Mathematics-Secret-Skills-Calculation/dp/0471467316/ref=si3_rdr_bb_product

Thanks for your replies

Docash1983

Todavianose
21st Jun 2008, 19:24
Can you use this method with for example 43x76, or is there another trick?

docash1983
23rd Jun 2008, 11:14
Hi guys, yes I did buy it and went through it from cover to cover. It does show a very different way of honing your basic skills in maths i.e. division, subtraction, multiplication, addition, squaring etc. However, using these methods in practical terms (by that I mean away from the examples it provides in the book) it was of little use. I was initially very impressed with the book but in the end found it very disappointing, for example it’s brilliant for questions such as 96 x 96 = 9216, where you are able to use 100 as a base number, for example:


96 x 96
(a) -4 -4

(b) 96 – 4 = 92 (your thousands and hundredths)
(C) 4x4 = 12 (your tens and units)

Answer 9216
a) you say 96 is below 100 by 4 units place them under the 96 on both sides, then
b) deduct one of 4’s (or any other number under the main number 96) which give you 92,
c) then multiply the numbers under the 96 so 4 x 4 = 16 and put on the end.

However, when doing sums like 43 x 76 the methods don’t work that well but there are ways of doing it. In the book he describes a method where you can use two base numbers here it becomes something like using base numbers 50 and 100.

The books downfalls really show up when trying to multiply massive numbers like 787 x 1675830 whereby the methods for base numbers as shown above just can’t work and therefore I found I had to resort to the old fashioned methods of multiplying individual numbers. Self admittedly I am pants at maths and was hoping this book would help, but I’m afraid it didn’t really cover all bases it only covered things up to a certain extent. It also lacks clear and through explanation in areas which may have helped the reader adapt the methods to their needs.

Hope this helps

Docash1983