Question

The ten’s digit of a number is twice its unit’s digit. The number obtained by interchanging the digits is 36 less than the original number. Find the original number

Answer 1

Answer:

Step-by-step explanation:

Let tens digit be x

And unit digit be y

Then number =10x+y

Interchanged number =10 y+x

And (tens digit is twice the unit )

That is, x=2y (equation 1)

Now according to the question

10 y+x=10x+y-36

9y =9x-36

y=x-4 (from equation 1)

y=2y-4

y=4

Then x=2y=2 (4)=8

The no is 84

Answer 2

let x be the digit at unit place and y be the digit at tens place

therefore the original number is 10y +x

according to 1st condition

y =2x......(1)

according to 2nd condition

10x+y=10y+x-36

10x-x+y-10y=-36

9x-9y=-36

dividing by 9 on both sides

x-y=-4.....(2)

substituting y =2x in equation (2)

x-2x=-4

-x=-4

x=4

the digit at uni place is 4 and digit at tens place =y=2x=8

therefore the original number

=10y+x

=10×8+4

=80+4

=84