math tricks:wanna be entertained

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photon
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math tricks:wanna be entertained

Unread post by photon » Sun May 01, 2011 10:46 pm

math tricks are very very interesting to a person (must be) and makes curious to math...none can deny that.
now it's the place where we post interesting tricks we know.... as any other forum couldn't be more suitable. here we will post the tricks we know,which attract people,shock people,make say "how you did it? :shock: ",which take attention to the beauty of math for people.
here I'm giving some tricks,....i think you may know them before.
1.9-a mysterious number:
very easy one.consider your birthday.let someone's birthday is 9 june,1984.
writing it :arrow: $9061984$
make it inversely arranged (the digits).we get :arrow: $4891609$
substract the smaller from the bigger.
$9061984-4891609=4170375$
add all the digits of $4170375$ :arrow: $4+1+7+0+3+7+5=27$......adding again :arrow: $2+7=9$
that how always we can get 9 for any 1 birthday. ;)
but it is not the matter if there is any birthday where that 9theory is not applicable.it is matter if the number arranged from the birthdate is palindromic(2nd march of 302 decade :arrow: 203302) or with consecutive 1 digit used (11th november,in 1111 :arrow: 11111111 ).may you have got why.......?
2.trick with 1089:
it is my very favourite one.also familiar.
take a 3 digit number no digit same.make it inversely arranged(like 123 :arrow: 321) .now substract the smaller from bigger.let the ans is $a$.make $a$ inversely arranged digits again.
now add $a$ and its inversed number and you will get 1089.....all the time :D
like 547 :arrow: 745
$745-547=198$
198 :arrow: 891
$198+891=1089$
there are infinite scopes for that.i mean you will get
2 digit :arrow: $9.11$
3 digit :arrow: $9.11^2$
4 digit :arrow: $9.11^3$
5digit :arrow: $9.11^4$
we can say if we take n digits' number (not be palindromic and like111111, 55555555) ,on that way stated above we will get $9.11^{n-1}$
by the way,can you find why it is 1089 always? :)
3.something about odds:
take an odd number.add 1 with it.divide it by 2.now square the odd we took and substract 1 from it .divide by 8.now tell me what you got after dividing by 2,i'll say what you got dividing 8.
actually the matter is,if we write
$(2n-1)^2=8k+1$
then you get,
\[k=\frac{n(n-1)}{2}............(1)\]
here n is dividing by 2 result and k is dividing 8 result.(1) no. equation is the theory to get k after knowing what is n.
did you notice k is the sum of 1st $n$ non-negative numbers?by the way,it is special to me because i found that trick myself! :lol:
so,what about you!post trick/s.....
Try not to become a man of success but rather to become a man of value.-Albert Einstein

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