Question

The sum of the digits of a two digit number is 9 also nine time this numbers is twice the number obtained by reversing the order of the digits. Find the number

Answer 1

Answer:

18

Step-by-step explanation:

digit is 1+8 = 9

and nine times the number means 9*9 = 81

by reversing the digits it is 18 i.e; 9+9( twice the number obtained)

Answer 2

Step-by-step explanation:

Let the unit digit be x and tens digit be y.

So, the number will be = 10y + x

After interchanging the digits the number becomes = 10x + y

It is given that, The sum of the digits of two digit number is 9. Therefore we get :]

x + y = 9.......(Equation i)

It is also given that, Nine times this number is twice the number obtained by reversing the order of the digits :]

9(10y + x) = 2(10x + y)

90y + 9x = 20x + 2y

90y - 2y = 20x - 9x

188y = 11x

x = 8y.......(Equation ii)

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Now,Putting the value of x = 8y in equation (i) we get :]

x + y = 9

8y + y = 9

9y = 9

y = 1

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Now, substitute the value of y in equation (ii) we get :]

x = 8y

x = 8(1)

x = 8

Therefore

The original number will be 10y + x = 10(1) + 8 = 18