It is easiest to explain with an example.
Suppose you have a number 4627.
Then the number obtained by reversing [the order of] its digits is 7264.
The difference between them is the bigger number minus the smaller number. So here it would be 7264 - 4627 = 2637.
3 and 6
36
28
The number is 36.
63
3 and 6
No, reversing the order of the digits of a two-digit prime number does not always result in a prime number.
3
If a number An consisting of n consecutive digits in ascending order is subtracted from the number An' obtained by reversing the digits of An, then the difference is always a constant. This constant is termed as the 'Unique number' Un as reported by me earlier in. For example, a 3-digit number 345 if subtracted from its reverse 543, yields a difference of 198. Thus U3 = 198. Another 3-digit number, say, 678 if subtracted from its reverse 876 will also yield the same difference, that is, 198. Thus for any number consisting of 3 consecutive digits, the Unique number U3 is always 198. Similarly for a number consisting of 4 consecutive digits, the Unique number U4 = 3087.
37
899
Yes.
36
86 8 + 6 = 14 86 - 68 = 18 The difference of a transposition (reversing the digits), is always divisible by 9. If you take the difference, in this case 18, and divide that by 9, your answer is 2. This will be the difference between the two digits (ie, 1 + 2 = 3, so transposing 13 and 31 results in a difference of 18. So does 24 and 42 or 35 and 53, etc). This helps you quickly solve the problem by taking one half of the sum of the digits (14), divide in half (7) and move 1 number in each direction (one being half of 2, the known difference between the digits) and you get 8 (7+1) and 6 (7-1). If your difference was 27, then the two digits would be 3 numbers apart (27 divided by 9 = 3) such as 14 and 41 or 25 and 52, etc. If the solution was 25 and 52: The two numbers add to 7 and the difference of the transposition is 27. The two numbers add to 7 - one half of 7 is 3.5 - move 1.5 (half of 3, 27/9) in either direction from 3.5 and you get your answer 5 (3.5+1.5) and 2 (3.5-1.5). Try it where the difference of the transposition is 36 (the difference in the digits will be 4) such as 37 and 73 or 48 and 84.
63
28
You are 80.