Q. 145.0( 4 Votes )

A two–digit number is such that the product of its digits is 18. When 63 is subtracted from the number, the digits interchange their places. Find the number.

Answer :

Let the units digit be ‘Y’, so the tens digit will be X.

the number is 10X + Y

X . Y =18 –––––– (i)


On simplifying further,

9X – 9Y – 63 = 0

X – Y – 7 = 0

Putting the value of from equation –––––– (i)

18 – Y2 – 7Y = 0

Y2 + 7Y – 18 = 0

On applying Sreedhracharya formula

Y = – 9 or 2

Y = 2 (Only Positive values)

X = 9

The number is 92 {9(10)+2}.

Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Get To Know About Quadratic Formula42 mins
Quiz | Knowing the Nature of Roots44 mins
Take a Dip Into Quadratic graphs32 mins
Foundation | Practice Important Questions for Foundation54 mins
Nature of Roots of Quadratic Equations51 mins
Getting Familiar with Nature of Roots of Quadratic Equations51 mins
Quadratic Equation: Previous Year NTSE Questions32 mins
Champ Quiz | Quadratic Equation33 mins
Balance the Chemical Equations49 mins
Understand The Concept of Quadratic Equation45 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
view all courses