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November 2nd, 2017, 04:06 PM   #1
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From: rasht iran

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how we can guess a last number from a 4number?

hello guys.
always i has hate from math but a persion asked a puzzle from me!
i can not understand he how can guess this !

for more pls read mt next... ( sorry for poor english - i hope you undestand me)

he told me write a 4number like

4321
and next write from back
1234
now do 4321 - 1234 and find answer.

4321-1234= 3087


he told me now say me 3 first number from your answer.
i told 308 and he told its 3087!!!


for new example:

i did 9345- 5439= 3906

i and say 390* .

but he know what is * !!!!
he guess * is 6 !!!!


but he with what algorithm can find it ?

with what algorithm i can find number of 4 fom a 4number?

------------------------------------------
thanks for your help, i am wait for give a good answer from you.

Last edited by edrisdolati; November 2nd, 2017 at 04:09 PM.
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November 2nd, 2017, 05:44 PM   #2
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what would you do if the reversed number is larger than the original?
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November 3rd, 2017, 01:45 AM   #3
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From: rasht iran

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Quote:
Originally Posted by romsek View Post
what would you do if the reversed number is larger than the original?
i not know really , dears anyone not know thai puzzle?
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November 3rd, 2017, 01:46 AM   #4
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i need for today, pls help me
thanks

www.landscapingarchitect.ir
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November 3rd, 2017, 04:52 AM   #5
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Your friend is using the idea of Modulus (to base 9).
4321 mod 9 = 1 (4321/9 = 480 rem 1). 4 + 3 + 2 + 1 = 10; 10/9 = 1 rem 1.
1234 mod 9 = 1 (1234/9 = 137 rem 1). Also 1 + 2 + 3 + 4 = 10; 10/9 = 1 rem 1.
The difference between the number chosen and that found by reversing its digits will always have modulus 0 to base 9 ie divisible by 9. So, knowing three digits, your friend finds a fourth that brings the total to a multiple of 9.
3 + 0 + 8 = 11, needs 7 to bring it to 18.
3 + 9 + 0 = 12, needs 6 to bring it to 18.
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November 3rd, 2017, 05:52 AM   #6
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From: rasht iran

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hmmmm game with math
jofo dear friend thanks for your help.
thanks
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