Let ten’s place digit = x then one’s place digit =2x+1 Since, number =10x+2x+1 =12x+1 After interchanging the digit’s new number will be 10(2x+1)+x =20x+10+x =21x+10 Now, 21x+10–12x–1=27 ⇒9x=27–9 ∴x=
18
9
=2 Since, 2x+1=2×2+1=5 Hence, original number =10×2+5=25