Question

In a two digit number Unite place Digit is twice
the ten's Place Digit. If we add 9 in the
original no. then Digits are interchange. Find
the number​

Answer 1

Let the tens place digit be a

Unit place digit = 2a+1

No. = 10(a) + (2a+1)

= 10a+2a+1

= 12a + 1

Reversed no. = 10(2a+1)+ a

= 20a+10 + a

= 21a + 10

According to question

Original no. +36 = Reversed no.

=> 12a+1 + 36 = 21a + 10

=> 21a-12a = 37 - 10

=> 9a = 27

=> a = 3

Unit place digit = 3

Tens place digit = 7

Required no. = 37