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प्रश्न
The sum of the digits of a 2-digit number is 9. Also, nine times this number is twice the number obtained by reversing the order of the digits. Find the number.
बेरीज
उत्तर
Let the number be 10x + y.
Given, x + y = 9 ...(i)
According to the question,
9(10x + y) = 2(10y + x)
∴ 90x + 9y = 20y + 2x
∴ 88x − 11y = 0
∴ 8x − y = 0 ...(ii)
On adding Eqs. (i) and (ii), we get
9x = 9
∴ x = 1
On substituting x = 1 in Eq. (i), we get
1 + y = 9
∴ y = 8
The number is 10x + y = 10 × 1 + 8 = 18
Therefore, x = 1 and y = 8 are the required digits and the number is 18.
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