Sainik School Entrance Exam 2019 Solved Paper

Question : 28 of 150

Marks: +1, -0

Sum of the digits of a two-digit number is 9 . If 9 is subtracted from the number, the digits interchange their places. The original number is

Solution:

(b) Suppose that, the original number

=10x+y

x+y=9.......................(1)

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

10 x+y-9=10 y+x

9 x-9 y-9=0

x-y=1...................(2)

After solving equation (1) and (2), we get

x=5

y=4

Hence, the original number

=54

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