Also it is not clear what means "to write a number in reverse". Either you need only output the original number in the reverse order on the console or you need to get a new number that is equal to the reversed original number.
cin >> number;
// This is our stringstream it will be used for converting int to string.
// This will hold the number in string form
// Use the stringstream to convert the int into a string
// Use the reverse function on the stringForm of the number here.
cout << stringNumber;
2) The second option would be to use just simple math to do it :).
Here is something to get you started with it.
X is a int and is the number you wish to convert
Y is a int and will hold the reverse of X
Hint: You will need a while loop.
1 2 3
y *= 10;
y += x % 10;
x /= 10;
Now if you don't have to use a integer to hold the number and you can use any type you wish, just use a string to hold it the number and call the reverse function on the string.