Number System
The sum of the digits of a two-digit number is 12, and the difference between the number and the number obtained by interchanging the two digits of the number is 18. Find the number.
Let the number be 10x + y.∴ x + y = 12 ...........(i)10x + y - (10x + x) = 18or 10x + y - 10y - x = 18or 9x - 9y = 18∴ x - y = 2From (i) and (ii), x = 7, y = 5∴ Number = 75
Let the consecutive odd number be x, x + 2, x + 4 and x + 6 respectively.According to the question x + x + 2 + x + 4 + x + 6 = 104 = 4x + 12 = 104 = 4x = 104 - 12 = 92∴ x = 92/4 = 23∴ Required number = x + 4= 23 + 4 = 27
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