Tuesday, October 06, 2009

The 1089 trick


Write down any 3 digit number in which the first and last digits differ by more than one.
For example 851.
Reverse the number.
158
Subtract the smaller number from the larger number.
851-158=693
Reverse the answer.
369
Add the last two amounts together.
369+693=1089

The answer is always 1089. Magic!

6 Comments:

Anonymous Anonymous said...

i knew Barclays Private got it wrong on the last statement.

6:06 am  
Blogger kinglear said...

Mathematics is something I know a little about ( I was a mathematical historian and economist at University) - and it is one of the purest, most beautiful things on this planet.
The MOST beautiful thing in it is the power of compound interest.
Now all I have to do is hang on to the cash for long enough....

12:05 pm  
Blogger Winchester whisperer said...

They meant 9801, Anon

Can you do the trick with cash, KL?

8:26 am  
Blogger kinglear said...

ww - I could if my wife, my children, my dog, my bank manager and my friends didn't spend it all first...
Actually that's unfair, its only the wife and the bank manager I object to...

11:38 am  
Blogger Winchester whisperer said...

Hi KL - I meant the monetary form of this trick which is as follows (in old money). Write down any number of pounds under 13, any number of shillings under 20 and any number of pence under 12. Then switch the pounds and pence numbers and subtract the smaller amount. Reverse the pounds and pence and add the numbers. The answer is always £12 18s 11d. For example:
£3 14s 9d
£9 14s 3d

Subtracting line 1 from line 2 gives £5 19s 6d

Reversing that gives £6 19s 5d

Adding those gives you £12 18s 11d

6:58 pm  
Blogger Welshcakes Limoncello said...

Too mathematical for me but I like the graphic!

11:11 pm  

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