Question

What is that number,wch is 9 times the sum of its digits? Answer:- 81 Please give a solution with proper explanation.

Answer 1

Solution:

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Given:

To find a number whose number is 9 times the sum of the digits,.

Let the number in tens digit be x,

Let the number in ones digit be y,.

Then the number is => 10x + y,.

&

The sum of the digits = x+y,.

It is said that it is 9 times the sum of the digits,.


10x + y = 9(x+y)

10x + y = 9x + 9y

x - 8y = 0..(i)

x = 8y ..(ii)

As $y \geq 2$ (as y is in ones digit, it can't exceed 9,.)

so,

y= 1,.

x= 8y

x = 8(1)

x = 8,.

The number is,

10x + y = 10(8) + 1 = 81,.

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                             Hope it Helps!!