Let the number be 10x + y; then xy = 8 ...(i) Also, 10x + y + 18 = 10y + x ⇒ 9(x – y) = – 18 ⇒ x – y = – 2 ...(ii) Now,(x+y)2=(x−y)2+4xy=(−2)2+4×8=36 ∴x+y=6 ...(iii) Solving the equations (ii) and (iii) we get, x = 2 and y = 4 Hence, number = 10 × 2 + 4 = 24