Question

Pick any three-digit counting number. Reverse the digits of the original number. The difference of these two numbers has a tens digit of 9.

Answer 1

As given,

Step 1: Pick any three-digit counting number

Lets pick the number 643

Step 2: Reverse the digits of the original number.

So, reverse becomes 346

Now, it says that the difference of these two numbers has a tens digit of 9.

Lets, check:

$643-346=297$

So, its true that the difference has a tens digit of 9.

Another example:

Lets take 449

So reverse is = 944

Difference = $944-449=495$

Here also the tens digit is 9.

So, the condition applies to all 3 digit numbers.