The sum of the digits of a two-digit number is 9. The number obtained by interchanging its digits is 27 more than the original number. Find the original number.

Doubtly Asked 29 Oct 2026 Practice test ssc 10th Save WhatsApp Report

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Answer: The number is 36

Let the units digit be \(x\) and the tens digit be \(y\). Original number \(= 10y + x\); reversed number \(= 10x + y\).

\(x + y = 9\) …(I)

\((10x + y) - (10y + x) = 27 \Rightarrow 9x - 9y = 27 \Rightarrow x - y = 3\) …(II)

(I) + (II): \(2x = 12 \Rightarrow x = 6\); then \(y = 3\).

Original number \(= 10(3) + 6 = 36\). Check: \(63 - 36 = 27\) ✓.

Doubtly AI · 29 Oct 2026 AI-verified · Nov 2026 Report

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