Question

11. The sum of digits of a two digit number is 9.
The digits are reversed when 9 is added to the
number. Find the number.​

Answer 1

Answer:

45

Step-by-step explanation:

Answer would be 45.

If you add 9 to it, you get 54, in which digits of 45 are reversed.

OK. Now the question is how to find it.

Let say tn be the first two-digit number.

Its value can be written as 10t+n , and we kno w t+n=9

Adding 9 to tn would make it reversed and thus its value would be 10n+t

Now we have

t+n=9 and

10t+n+9=10n+t

⇒9t+9=9n

⇒t+1=n⇒t−n=−1

Therefore from t+n=9

We will have, 2t=8⇒t=4

and t+n=9 gives n=5

So the required number tn=10t+n=45 .