| I once heard of a similar method to do this, however I have developed it into a DHV routine.
Thell her that you want to show her something cool. Tell her to get her phone out and put it on the table in front of her.
Now make a bet that you can multiply any two ninety numbers in your head before she can find her phones calculator.
Obviously, you will win, earn a round of applause, a drink perhaps, and it shows that you are inteligent. Afterwards, of course, you will tell her that if she teaches you someting cool, you will show her how it is done.
How is it done?
Easy. The formula I wrote for it is if ab=c,d,e,f
e,f=(100-a)(100-b)
and
c,d= a-(100-b)
Sound complicated?
Let me put it another way.
let us say you have the numbers 96 and 93 to multiply.
Here it is step by step.
1. Get her to tell you two numbers in their ninetys. Say she picks 93 and 96.
2. Think 'how many more do I need for each ot make 100? In this case, 7 and 4
3. Multiply those numbers together. This will make the last two digits, or 28.
4.Now, thinking diagonally, take 4 from 93. which gives you 89.
93 96
7 4
That is (diagonally) 93-4, or 96- 7.
The answer is 89.
5. Put it all together to make 8928.
If you practice this enough, you sdhould be able to do it in under ten seconds. Just make sure she can't find her phone calculator in that time.
Trust me, it looks harder written down. To explain it in the field is easy also, if you know the method inside out. I have gotten many IOI's using this.[/b]
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