Practice Test Discussion

Q)

The number obtained by interchanging the digits of a two digit number is less than the original number by 63. If the sum of the digits of the number is 11, what is the original number?

[SBI(PO), 2008]

    • Explanation

    Let the original number be 10x+y

    Number obtained upon interchanging the digits is x+10y

    According to the question, difference been the original number and the number after interchanging is 63

    So, (10x+y)-(x+10y)=63

    ⇒ 9(x-y)=63

    ⇒ x-y =7---Eq1

    It is given that x+y=11---Eq2

    Upon adding adding Eq1 and Eq2 we get 

    ⇒ 2x=18

    Therefore x=9 and y=2

    ∴ so the original number is [(10x9)+2]=92

    Hence option B is correct.

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