Quizzes & Puzzles1 min ago
Please tell me!
8 Answers
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Enter portfolio then wizardry.
I know there are others like this but I just cant see how it is done.
Answers
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For more on marking an answer as the "Best Answer", please visit our FAQ.A slightly more Vordermanesque answer.
If the number you choose has tens digit 'x' and ones digit 'y' then:
The value of the number is 10x+y
The total of the digits is x+y
The value of the number less the total of the digits is
(10x + y) -( x +y) = 10x + y - x - y which is 9x
As x must be a whole number greater than 1, the 'magic' number is always a multiple of 9.
Each multiple of 9 is given the same symbol.
QED
If the number you choose has tens digit 'x' and ones digit 'y' then:
The value of the number is 10x+y
The total of the digits is x+y
The value of the number less the total of the digits is
(10x + y) -( x +y) = 10x + y - x - y which is 9x
As x must be a whole number greater than 1, the 'magic' number is always a multiple of 9.
Each multiple of 9 is given the same symbol.
QED